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/*
* linux/mm/filemap.c
*
* Copyright (C) 1994-1999 Linus Torvalds
*/
/*
* This file handles the generic file mmap semantics used by
* most "normal" filesystems (but you don't /have/ to use this:
* the NFS filesystem used to do this differently, for example)
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/locks.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/smp_lock.h>
#include <linux/blkdev.h>
#include <linux/file.h>
#include <linux/swapctl.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/iobuf.h>
#include <linux/compiler.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/mman.h>
#include <linux/highmem.h>
/*
* Shared mappings implemented 30.11.1994. It's not fully working yet,
* though.
*
* Shared mappings now work. 15.8.1995 Bruno.
*
* finished 'unifying' the page and buffer cache and SMP-threaded the
* page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
*
* SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
*/
atomic_t page_cache_size = ATOMIC_INIT(0);
unsigned int page_hash_bits;
struct page **page_hash_table;
int vm_max_readahead = 31;
int vm_min_readahead = 3;
EXPORT_SYMBOL(vm_max_readahead);
EXPORT_SYMBOL(vm_min_readahead);
spinlock_t pagecache_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
/*
* NOTE: to avoid deadlocking you must never acquire the pagemap_lru_lock
* with the pagecache_lock held.
*
* Ordering:
* swap_lock ->
* pagemap_lru_lock ->
* pagecache_lock
*/
spinlock_t pagemap_lru_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
#define CLUSTER_PAGES (1 << page_cluster)
#define CLUSTER_OFFSET(x) (((x) >> page_cluster) << page_cluster)
static void FASTCALL(add_page_to_hash_queue(struct page * page, struct page **p));
static void add_page_to_hash_queue(struct page * page, struct page **p)
{
struct page *next = *p;
*p = page;
page->next_hash = next;
page->pprev_hash = p;
if (next)
next->pprev_hash = &page->next_hash;
if (page->buffers)
PAGE_BUG(page);
atomic_inc(&page_cache_size);
}
static inline void add_page_to_inode_queue(struct address_space *mapping, struct page * page)
{
struct list_head *head = &mapping->clean_pages;
mapping->nrpages++;
list_add(&page->list, head);
page->mapping = mapping;
}
static inline void remove_page_from_inode_queue(struct page * page)
{
struct address_space * mapping = page->mapping;
mapping->nrpages--;
list_del(&page->list);
page->mapping = NULL;
}
static inline void remove_page_from_hash_queue(struct page * page)
{
struct page *next = page->next_hash;
struct page **pprev = page->pprev_hash;
if (next)
next->pprev_hash = pprev;
*pprev = next;
page->pprev_hash = NULL;
atomic_dec(&page_cache_size);
}
/*
* Remove a page from the page cache and free it. Caller has to make
* sure the page is locked and that nobody else uses it - or that usage
* is safe.
*/
void __remove_inode_page(struct page *page)
{
if (DelallocPage(page)) {
printk("Delalloc page %p removed from inode\n", page);
BUG();
}
if (PageDirty(page)) BUG();
remove_page_from_inode_queue(page);
remove_page_from_hash_queue(page);
}
void remove_inode_page(struct page *page)
{
if (!PageLocked(page))
PAGE_BUG(page);
spin_lock(&pagecache_lock);
__remove_inode_page(page);
spin_unlock(&pagecache_lock);
}
static inline int sync_page(struct page *page)
{
struct address_space *mapping = page->mapping;
if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
return mapping->a_ops->sync_page(page);
return 0;
}
/*
* Add a page to the dirty page list.
*/
void set_page_dirty(struct page *page)
{
if (!test_and_set_bit(PG_dirty, &page->flags)) {
struct address_space *mapping = page->mapping;
if (mapping) {
spin_lock(&pagecache_lock);
list_del(&page->list);
list_add(&page->list, &mapping->dirty_pages);
spin_unlock(&pagecache_lock);
if (mapping->host)
mark_inode_dirty_pages(mapping->host);
}
}
}
/**
* invalidate_inode_pages - Invalidate all the unlocked pages of one inode
* @inode: the inode which pages we want to invalidate
*
* This function only removes the unlocked pages, if you want to
* remove all the pages of one inode, you must call truncate_inode_pages.
*/
void invalidate_inode_pages(struct inode * inode)
{
struct list_head *head, *curr;
struct page * page;
head = &inode->i_mapping->clean_pages;
spin_lock(&pagemap_lru_lock);
spin_lock(&pagecache_lock);
curr = head->next;
while (curr != head) {
page = list_entry(curr, struct page, list);
curr = curr->next;
/* We cannot invalidate something in dirty.. */
if (PageDirty(page))
continue;
/* ..or locked */
if (TryLockPage(page))
continue;
if (page->buffers && !try_to_free_buffers(page, 0))
goto unlock;
if (page_count(page) != 1)
goto unlock;
__lru_cache_del(page);
__remove_inode_page(page);
UnlockPage(page);
page_cache_release(page);
continue;
unlock:
UnlockPage(page);
continue;
}
spin_unlock(&pagecache_lock);
spin_unlock(&pagemap_lru_lock);
}
static int do_flushpage(struct page *page, unsigned long offset)
{
int (*flushpage) (struct page *, unsigned long);
flushpage = page->mapping->a_ops->flushpage;
if (flushpage)
return (*flushpage)(page, offset);
return block_flushpage(page, offset);
}
static inline void truncate_partial_page(struct page *page, unsigned partial)
{
memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
if (page->buffers)
do_flushpage(page, partial);
}
static void truncate_complete_page(struct page *page)
{
/* Leave it on the LRU if it gets converted into anonymous buffers */
if (!page->buffers || do_flushpage(page, 0))
lru_cache_del(page);
/*
* We remove the page from the page cache _after_ we have
* destroyed all buffer-cache references to it. Otherwise some
* other process might think this inode page is not in the
* page cache and creates a buffer-cache alias to it causing
* all sorts of fun problems ...
*/
ClearPageDirty(page);
ClearPageUptodate(page);
remove_inode_page(page);
page_cache_release(page);
}
static int FASTCALL(truncate_list_pages(struct list_head *, unsigned long, unsigned *));
static int truncate_list_pages(struct list_head *head, unsigned long start, unsigned *partial)
{
struct list_head *curr;
struct page * page;
int unlocked = 0;
restart:
curr = head->prev;
while (curr != head) {
unsigned long offset;
page = list_entry(curr, struct page, list);
offset = page->index;
/* Is one of the pages to truncate? */
if ((offset >= start) || (*partial && (offset + 1) == start)) {
int failed;
page_cache_get(page);
failed = TryLockPage(page);
list_del(head);
if (!failed)
/* Restart after this page */
list_add_tail(head, curr);
else
/* Restart on this page */
list_add(head, curr);
spin_unlock(&pagecache_lock);
unlocked = 1;
if (!failed) {
if (*partial && (offset + 1) == start) {
truncate_partial_page(page, *partial);
*partial = 0;
} else
truncate_complete_page(page);
UnlockPage(page);
} else
wait_on_page(page);
page_cache_release(page);
if (current->need_resched) {
__set_current_state(TASK_RUNNING);
schedule();
}
spin_lock(&pagecache_lock);
goto restart;
}
curr = curr->prev;
}
return unlocked;
}
/**
* truncate_inode_pages - truncate *all* the pages from an offset
* @mapping: mapping to truncate
* @lstart: offset from with to truncate
*
* Truncate the page cache at a set offset, removing the pages
* that are beyond that offset (and zeroing out partial pages).
* If any page is locked we wait for it to become unlocked.
*/
void truncate_inode_pages(struct address_space * mapping, loff_t lstart)
{
unsigned long start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
int unlocked;
spin_lock(&pagecache_lock);
do {
unlocked = truncate_list_pages(&mapping->clean_pages, start, &partial);
unlocked |= truncate_list_pages(&mapping->dirty_pages, start, &partial);
unlocked |= truncate_list_pages(&mapping->locked_pages, start, &partial);
} while (unlocked);
/* Traversed all three lists without dropping the lock */
spin_unlock(&pagecache_lock);
}
static inline int invalidate_this_page2(struct page * page,
struct list_head * curr,
struct list_head * head)
{
int unlocked = 1;
/*
* The page is locked and we hold the pagecache_lock as well
* so both page_count(page) and page->buffers stays constant here.
*/
if (page_count(page) == 1 + !!page->buffers) {
/* Restart after this page */
list_del(head);
list_add_tail(head, curr);
page_cache_get(page);
spin_unlock(&pagecache_lock);
truncate_complete_page(page);
} else {
if (page->buffers) {
/* Restart after this page */
list_del(head);
list_add_tail(head, curr);
page_cache_get(page);
spin_unlock(&pagecache_lock);
block_invalidate_page(page);
} else
unlocked = 0;
ClearPageDirty(page);
ClearPageUptodate(page);
}
return unlocked;
}
static int FASTCALL(invalidate_list_pages2(struct list_head *));
static int invalidate_list_pages2(struct list_head *head)
{
struct list_head *curr;
struct page * page;
int unlocked = 0;
restart:
curr = head->prev;
while (curr != head) {
page = list_entry(curr, struct page, list);
if (!TryLockPage(page)) {
int __unlocked;
__unlocked = invalidate_this_page2(page, curr, head);
UnlockPage(page);
unlocked |= __unlocked;
if (!__unlocked) {
curr = curr->prev;
continue;
}
} else {
/* Restart on this page */
list_del(head);
list_add(head, curr);
page_cache_get(page);
spin_unlock(&pagecache_lock);
unlocked = 1;
wait_on_page(page);
}
page_cache_release(page);
if (current->need_resched) {
__set_current_state(TASK_RUNNING);
schedule();
}
spin_lock(&pagecache_lock);
goto restart;
}
return unlocked;
}
/**
* invalidate_inode_pages2 - Clear all the dirty bits around if it can't
* free the pages because they're mapped.
* @mapping: the address_space which pages we want to invalidate
*/
void invalidate_inode_pages2(struct address_space * mapping)
{
int unlocked;
spin_lock(&pagecache_lock);
do {
unlocked = invalidate_list_pages2(&mapping->clean_pages);
unlocked |= invalidate_list_pages2(&mapping->dirty_pages);
unlocked |= invalidate_list_pages2(&mapping->locked_pages);
} while (unlocked);
spin_unlock(&pagecache_lock);
}
static inline struct page * __find_page_nolock(struct address_space *mapping, unsigned long offset, struct page *page)
{
goto inside;
for (;;) {
page = page->next_hash;
inside:
if (!page)
goto not_found;
if (page->mapping != mapping)
continue;
if (page->index == offset)
break;
}
not_found:
return page;
}
static int do_buffer_fdatasync(struct list_head *head, unsigned long start, unsigned long end, int (*fn)(struct page *))
{
struct list_head *curr;
struct page *page;
int retval = 0;
spin_lock(&pagecache_lock);
curr = head->next;
while (curr != head) {
page = list_entry(curr, struct page, list);
curr = curr->next;
if (!page->buffers)
continue;
if (page->index >= end)
continue;
if (page->index < start)
continue;
page_cache_get(page);
spin_unlock(&pagecache_lock);
lock_page(page);
/* The buffers could have been free'd while we waited for the page lock */
if (page->buffers)
retval |= fn(page);
UnlockPage(page);
spin_lock(&pagecache_lock);
curr = page->list.next;
page_cache_release(page);
}
spin_unlock(&pagecache_lock);
return retval;
}
/*
* Two-stage data sync: first start the IO, then go back and
* collect the information..
*/
int generic_buffer_fdatasync(struct inode *inode, unsigned long start_idx, unsigned long end_idx)
{
int retval;
/* writeout dirty buffers on pages from both clean and dirty lists */
retval = do_buffer_fdatasync(&inode->i_mapping->dirty_pages, start_idx, end_idx, writeout_one_page);
retval |= do_buffer_fdatasync(&inode->i_mapping->clean_pages, start_idx, end_idx, writeout_one_page);
retval |= do_buffer_fdatasync(&inode->i_mapping->locked_pages, start_idx, end_idx, writeout_one_page);
/* now wait for locked buffers on pages from both clean and dirty lists */
retval |= do_buffer_fdatasync(&inode->i_mapping->dirty_pages, start_idx, end_idx, waitfor_one_page);
retval |= do_buffer_fdatasync(&inode->i_mapping->clean_pages, start_idx, end_idx, waitfor_one_page);
retval |= do_buffer_fdatasync(&inode->i_mapping->locked_pages, start_idx, end_idx, waitfor_one_page);
return retval;
}
/*
* In-memory filesystems have to fail their
* writepage function - and this has to be
* worked around in the VM layer..
*
* We
* - mark the page dirty again (but do NOT
* add it back to the inode dirty list, as
* that would livelock in fdatasync)
* - activate the page so that the page stealer
* doesn't try to write it out over and over
* again.
*/
int fail_writepage(struct page *page)
{
/* Only activate on memory-pressure, not fsync.. */
if (PageLaunder(page)) {
activate_page(page);
SetPageReferenced(page);
}
/* Set the page dirty again, unlock */
SetPageDirty(page);
UnlockPage(page);
return 0;
}
EXPORT_SYMBOL(fail_writepage);
/**
* filemap_fdatasync - walk the list of dirty pages of the given address space
* and writepage() all of them.
*
* @mapping: address space structure to write
*
*/
int filemap_fdatasync(struct address_space * mapping)
{
int ret = 0;
int (*writepage)(struct page *) = mapping->a_ops->writepage;
spin_lock(&pagecache_lock);
while (!list_empty(&mapping->dirty_pages)) {
struct page *page = list_entry(mapping->dirty_pages.next, struct page, list);
list_del(&page->list);
list_add(&page->list, &mapping->locked_pages);
if (!PageDirty(page))
continue;
page_cache_get(page);
spin_unlock(&pagecache_lock);
lock_page(page);
if (PageDirty(page)) {
int err;
ClearPageDirty(page);
err = writepage(page);
if (err && !ret)
ret = err;
} else
UnlockPage(page);
page_cache_release(page);
spin_lock(&pagecache_lock);
}
spin_unlock(&pagecache_lock);
return ret;
}
/**
* filemap_fdatawait - walk the list of locked pages of the given address space
* and wait for all of them.
*
* @mapping: address space structure to wait for
*
*/
int filemap_fdatawait(struct address_space * mapping)
{
int ret = 0;
spin_lock(&pagecache_lock);
while (!list_empty(&mapping->locked_pages)) {
struct page *page = list_entry(mapping->locked_pages.next, struct page, list);
list_del(&page->list);
list_add(&page->list, &mapping->clean_pages);
if (!PageLocked(page))
continue;
page_cache_get(page);
spin_unlock(&pagecache_lock);
___wait_on_page(page);
if (PageError(page))
ret = -EIO;
page_cache_release(page);
spin_lock(&pagecache_lock);
}
spin_unlock(&pagecache_lock);
return ret;
}
/*
* Add a page to the inode page cache.
*
* The caller must have locked the page and
* set all the page flags correctly..
*/
void add_to_page_cache_locked(struct page * page, struct address_space *mapping, unsigned long index)
{
if (!PageLocked(page))
BUG();
page->index = index;
page_cache_get(page);
spin_lock(&pagecache_lock);
add_page_to_inode_queue(mapping, page);
add_page_to_hash_queue(page, page_hash(mapping, index));
spin_unlock(&pagecache_lock);
lru_cache_add(page);
}
/*
* This adds a page to the page cache, starting out as locked,
* owned by us, but unreferenced, not uptodate and with no errors.
*/
static inline void __add_to_page_cache(struct page * page,
struct address_space *mapping, unsigned long offset,
struct page **hash)
{
unsigned long flags;
flags = page->flags & ~(1 << PG_uptodate | 1 << PG_error | 1 << PG_dirty | 1 << PG_referenced | 1 << PG_arch_1 | 1 << PG_checked);
page->flags = flags | (1 << PG_locked);
page_cache_get(page);
page->index = offset;
add_page_to_inode_queue(mapping, page);
add_page_to_hash_queue(page, hash);
}
void add_to_page_cache(struct page * page, struct address_space * mapping, unsigned long offset)
{
spin_lock(&pagecache_lock);
__add_to_page_cache(page, mapping, offset, page_hash(mapping, offset));
spin_unlock(&pagecache_lock);
lru_cache_add(page);
}
int add_to_page_cache_unique(struct page * page,
struct address_space *mapping, unsigned long offset,
struct page **hash)
{
int err;
struct page *alias;
spin_lock(&pagecache_lock);
alias = __find_page_nolock(mapping, offset, *hash);
err = 1;
if (!alias) {
__add_to_page_cache(page,mapping,offset,hash);
err = 0;
}
spin_unlock(&pagecache_lock);
if (!err)
lru_cache_add(page);
return err;
}
/*
* This adds the requested page to the page cache if it isn't already there,
* and schedules an I/O to read in its contents from disk.
*/
static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
static int page_cache_read(struct file * file, unsigned long offset)
{
struct address_space *mapping = file->f_dentry->d_inode->i_mapping;
struct page **hash = page_hash(mapping, offset);
struct page *page;
spin_lock(&pagecache_lock);
page = __find_page_nolock(mapping, offset, *hash);
spin_unlock(&pagecache_lock);
if (page)
return 0;
page = page_cache_alloc(mapping);
if (!page)
return -ENOMEM;
if (!add_to_page_cache_unique(page, mapping, offset, hash)) {
int error = mapping->a_ops->readpage(file, page);
page_cache_release(page);
return error;
}
/*
* We arrive here in the unlikely event that someone
* raced with us and added our page to the cache first.
*/
page_cache_release(page);
return 0;
}
/*
* Read in an entire cluster at once. A cluster is usually a 64k-
* aligned block that includes the page requested in "offset."
*/
static int FASTCALL(read_cluster_nonblocking(struct file * file, unsigned long offset,
unsigned long filesize));
static int read_cluster_nonblocking(struct file * file, unsigned long offset,
unsigned long filesize)
{
unsigned long pages = CLUSTER_PAGES;
offset = CLUSTER_OFFSET(offset);
while ((pages-- > 0) && (offset < filesize)) {
int error = page_cache_read(file, offset);
if (error < 0)
return error;
offset ++;
}
return 0;
}
/*
* Wait for a page to get unlocked.
*
* This must be called with the caller "holding" the page,
* ie with increased "page->count" so that the page won't
* go away during the wait..
*/
void ___wait_on_page(struct page *page)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
add_wait_queue(&page->wait, &wait);
do {
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (!PageLocked(page))
break;
sync_page(page);
schedule();
} while (PageLocked(page));
tsk->state = TASK_RUNNING;
remove_wait_queue(&page->wait, &wait);
}
void unlock_page(struct page *page)
{
clear_bit(PG_launder, &(page)->flags);
smp_mb__before_clear_bit();
if (!test_and_clear_bit(PG_locked, &(page)->flags))
BUG();
smp_mb__after_clear_bit();
if (waitqueue_active(&(page)->wait))
wake_up(&(page)->wait);
}
/*
* Get a lock on the page, assuming we need to sleep
* to get it..
*/
static void __lock_page(struct page *page)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
add_wait_queue_exclusive(&page->wait, &wait);
for (;;) {
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (PageLocked(page)) {
sync_page(page);
schedule();
}
if (!TryLockPage(page))
break;
}
tsk->state = TASK_RUNNING;
remove_wait_queue(&page->wait, &wait);
}
/*
* Get an exclusive lock on the page, optimistically
* assuming it's not locked..
*/
void lock_page(struct page *page)
{
if (TryLockPage(page))
__lock_page(page);
}
/*
* a rather lightweight function, finding and getting a reference to a
* hashed page atomically.
*/
struct page * __find_get_page(struct address_space *mapping,
unsigned long offset, struct page **hash)
{
struct page *page;
/*
* We scan the hash list read-only. Addition to and removal from
* the hash-list needs a held write-lock.
*/
spin_lock(&pagecache_lock);
page = __find_page_nolock(mapping, offset, *hash);
if (page)
page_cache_get(page);
spin_unlock(&pagecache_lock);
return page;
}
/*
* Same as above, but trylock it instead of incrementing the count.
*/
struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
{
struct page *page;
struct page **hash = page_hash(mapping, offset);
spin_lock(&pagecache_lock);
page = __find_page_nolock(mapping, offset, *hash);
if (page) {
if (TryLockPage(page))
page = NULL;
}
spin_unlock(&pagecache_lock);
return page;
}
/*
* Must be called with the pagecache lock held,
* will return with it held (but it may be dropped
* during blocking operations..
*/
static struct page * FASTCALL(__find_lock_page_helper(struct address_space *, unsigned long, struct page *));
static struct page * __find_lock_page_helper(struct address_space *mapping,
unsigned long offset, struct page *hash)
{
struct page *page;
/*
* We scan the hash list read-only. Addition to and removal from
* the hash-list needs a held write-lock.
*/
repeat:
page = __find_page_nolock(mapping, offset, hash);
if (page) {
page_cache_get(page);
if (TryLockPage(page)) {
spin_unlock(&pagecache_lock);
lock_page(page);
spin_lock(&pagecache_lock);
/* Has the page been re-allocated while we slept? */
if (page->mapping != mapping || page->index != offset) {
UnlockPage(page);
page_cache_release(page);
goto repeat;
}
}
}
return page;
}
/*
* Same as the above, but lock the page too, verifying that
* it's still valid once we own it.
*/
struct page * __find_lock_page (struct address_space *mapping,
unsigned long offset, struct page **hash)
{
struct page *page;
spin_lock(&pagecache_lock);
page = __find_lock_page_helper(mapping, offset, *hash);
spin_unlock(&pagecache_lock);
return page;
}
/*
* Same as above, but create the page if required..
*/
struct page * find_or_create_page(struct address_space *mapping, unsigned long index, unsigned int gfp_mask)
{
struct page *page;
struct page **hash = page_hash(mapping, index);
spin_lock(&pagecache_lock);
page = __find_lock_page_helper(mapping, index, *hash);
spin_unlock(&pagecache_lock);
if (!page) {
struct page *newpage = alloc_page(gfp_mask);
if (newpage) {
spin_lock(&pagecache_lock);
page = __find_lock_page_helper(mapping, index, *hash);
if (likely(!page)) {
page = newpage;
__add_to_page_cache(page, mapping, index, hash);
newpage = NULL;
}
spin_unlock(&pagecache_lock);
if (newpage == NULL)
lru_cache_add(page);
else
page_cache_release(newpage);
}
}
return page;
}
/*
* Returns locked page at given index in given cache, creating it if needed.
*/
struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
{
return find_or_create_page(mapping, index, mapping->gfp_mask);
}
/*
* Same as grab_cache_page, but do not wait if the page is unavailable.
* This is intended for speculative data generators, where the data can
* be regenerated if the page couldn't be grabbed. This routine should
* be safe to call while holding the lock for another page.
*/
struct page *grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
{
struct page *page, **hash;
hash = page_hash(mapping, index);
page = __find_get_page(mapping, index, hash);
if ( page ) {
if ( !TryLockPage(page) ) {
/* Page found and locked */
/* This test is overly paranoid, but what the heck... */
if ( unlikely(page->mapping != mapping || page->index != index) ) {
/* Someone reallocated this page under us. */
UnlockPage(page);
page_cache_release(page);
return NULL;
} else {
return page;
}
} else {
/* Page locked by someone else */
page_cache_release(page);
return NULL;
}
}
page = page_cache_alloc(mapping);
if ( unlikely(!page) )
return NULL; /* Failed to allocate a page */
if ( unlikely(add_to_page_cache_unique(page, mapping, index, hash)) ) {
/* Someone else grabbed the page already. */
page_cache_release(page);
return NULL;
}
return page;
}
#if 0
#define PROFILE_READAHEAD
#define DEBUG_READAHEAD
#endif
/*
* Read-ahead profiling information
* --------------------------------
* Every PROFILE_MAXREADCOUNT, the following information is written
* to the syslog:
* Percentage of asynchronous read-ahead.
* Average of read-ahead fields context value.
* If DEBUG_READAHEAD is defined, a snapshot of these fields is written
* to the syslog.
*/
#ifdef PROFILE_READAHEAD
#define PROFILE_MAXREADCOUNT 1000
static unsigned long total_reada;
static unsigned long total_async;
static unsigned long total_ramax;
static unsigned long total_ralen;
static unsigned long total_rawin;
static void profile_readahead(int async, struct file *filp)
{
unsigned long flags;
++total_reada;
if (async)
++total_async;
total_ramax += filp->f_ramax;
total_ralen += filp->f_ralen;
total_rawin += filp->f_rawin;
if (total_reada > PROFILE_MAXREADCOUNT) {
save_flags(flags);
cli();
if (!(total_reada > PROFILE_MAXREADCOUNT)) {
restore_flags(flags);
return;
}
printk("Readahead average: max=%ld, len=%ld, win=%ld, async=%ld%%\n",
total_ramax/total_reada,
total_ralen/total_reada,
total_rawin/total_reada,
(total_async*100)/total_reada);
#ifdef DEBUG_READAHEAD
printk("Readahead snapshot: max=%ld, len=%ld, win=%ld, raend=%Ld\n",
filp->f_ramax, filp->f_ralen, filp->f_rawin, filp->f_raend);
#endif
total_reada = 0;
total_async = 0;
total_ramax = 0;
total_ralen = 0;
total_rawin = 0;
restore_flags(flags);
}
}
#endif /* defined PROFILE_READAHEAD */
/*
* Read-ahead context:
* -------------------
* The read ahead context fields of the "struct file" are the following:
* - f_raend : position of the first byte after the last page we tried to
* read ahead.
* - f_ramax : current read-ahead maximum size.
* - f_ralen : length of the current IO read block we tried to read-ahead.
* - f_rawin : length of the current read-ahead window.
* if last read-ahead was synchronous then
* f_rawin = f_ralen
* otherwise (was asynchronous)
* f_rawin = previous value of f_ralen + f_ralen
*
* Read-ahead limits:
* ------------------
* MIN_READAHEAD : minimum read-ahead size when read-ahead.
* MAX_READAHEAD : maximum read-ahead size when read-ahead.
*
* Synchronous read-ahead benefits:
* --------------------------------
* Using reasonable IO xfer length from peripheral devices increase system
* performances.
* Reasonable means, in this context, not too large but not too small.
* The actual maximum value is:
* MAX_READAHEAD + PAGE_CACHE_SIZE = 76k is CONFIG_READA_SMALL is undefined
* and 32K if defined (4K page size assumed).
*
* Asynchronous read-ahead benefits:
* ---------------------------------
* Overlapping next read request and user process execution increase system
* performance.
*
* Read-ahead risks:
* -----------------
* We have to guess which further data are needed by the user process.
* If these data are often not really needed, it's bad for system
* performances.
* However, we know that files are often accessed sequentially by
* application programs and it seems that it is possible to have some good
* strategy in that guessing.
* We only try to read-ahead files that seems to be read sequentially.
*
* Asynchronous read-ahead risks:
* ------------------------------
* In order to maximize overlapping, we must start some asynchronous read
* request from the device, as soon as possible.
* We must be very careful about:
* - The number of effective pending IO read requests.
* ONE seems to be the only reasonable value.
* - The total memory pool usage for the file access stream.
* This maximum memory usage is implicitly 2 IO read chunks:
* 2*(MAX_READAHEAD + PAGE_CACHE_SIZE) = 156K if CONFIG_READA_SMALL is undefined,
* 64k if defined (4K page size assumed).
*/
static inline int get_max_readahead(struct inode * inode)
{
if (!inode->i_dev || !max_readahead[MAJOR(inode->i_dev)])
return vm_max_readahead;
return max_readahead[MAJOR(inode->i_dev)][MINOR(inode->i_dev)];
}
static void generic_file_readahead(int reada_ok,
struct file * filp, struct inode * inode,
struct page * page)
{
unsigned long end_index;
unsigned long index = page->index;
unsigned long max_ahead, ahead;
unsigned long raend;
int max_readahead = get_max_readahead(inode);
end_index = inode->i_size >> PAGE_CACHE_SHIFT;
raend = filp->f_raend;
max_ahead = 0;
/*
* The current page is locked.
* If the current position is inside the previous read IO request, do not
* try to reread previously read ahead pages.
* Otherwise decide or not to read ahead some pages synchronously.
* If we are not going to read ahead, set the read ahead context for this
* page only.
*/
if (PageLocked(page)) {
if (!filp->f_ralen || index >= raend || index + filp->f_rawin < raend) {
raend = index;
if (raend < end_index)
max_ahead = filp->f_ramax;
filp->f_rawin = 0;
filp->f_ralen = 1;
if (!max_ahead) {
filp->f_raend = index + filp->f_ralen;
filp->f_rawin += filp->f_ralen;
}
}
}
/*
* The current page is not locked.
* If we were reading ahead and,
* if the current max read ahead size is not zero and,
* if the current position is inside the last read-ahead IO request,
* it is the moment to try to read ahead asynchronously.
* We will later force unplug device in order to force asynchronous read IO.
*/
else if (reada_ok && filp->f_ramax && raend >= 1 &&
index <= raend && index + filp->f_ralen >= raend) {
/*
* Add ONE page to max_ahead in order to try to have about the same IO max size
* as synchronous read-ahead (MAX_READAHEAD + 1)*PAGE_CACHE_SIZE.
* Compute the position of the last page we have tried to read in order to
* begin to read ahead just at the next page.
*/
raend -= 1;
if (raend < end_index)
max_ahead = filp->f_ramax + 1;
if (max_ahead) {
filp->f_rawin = filp->f_ralen;
filp->f_ralen = 0;
reada_ok = 2;
}
}
/*
* Try to read ahead pages.
* We hope that ll_rw_blk() plug/unplug, coalescence, requests sort and the
* scheduler, will work enough for us to avoid too bad actuals IO requests.
*/
ahead = 0;
while (ahead < max_ahead) {
ahead ++;
if ((raend + ahead) >= end_index)
break;
if (page_cache_read(filp, raend + ahead) < 0)
break;
}
/*
* If we tried to read ahead some pages,
* If we tried to read ahead asynchronously,
* Try to force unplug of the device in order to start an asynchronous
* read IO request.
* Update the read-ahead context.
* Store the length of the current read-ahead window.
* Double the current max read ahead size.
* That heuristic avoid to do some large IO for files that are not really
* accessed sequentially.
*/
if (ahead) {
filp->f_ralen += ahead;
filp->f_rawin += filp->f_ralen;
filp->f_raend = raend + ahead + 1;
filp->f_ramax += filp->f_ramax;
if (filp->f_ramax > max_readahead)
filp->f_ramax = max_readahead;
#ifdef PROFILE_READAHEAD
profile_readahead((reada_ok == 2), filp);
#endif
}
return;
}
/*
* Mark a page as having seen activity.
*
* If it was already so marked, move it
* to the active queue and drop the referenced
* bit. Otherwise, just mark it for future
* action..
*/
void mark_page_accessed(struct page *page)
{
if (!PageActive(page) && PageReferenced(page)) {
activate_page(page);
ClearPageReferenced(page);
return;
}
/* Mark the page referenced, AFTER checking for previous usage.. */
SetPageReferenced(page);
}
EXPORT_SYMBOL(mark_page_accessed);
/*
* This is a generic file read routine, and uses the
* inode->i_op->readpage() function for the actual low-level
* stuff.
*
* This is really ugly. But the goto's actually try to clarify some
* of the logic when it comes to error handling etc.
*/
void do_generic_file_read(struct file * filp, loff_t *ppos, read_descriptor_t * desc, read_actor_t actor)
{
struct address_space *mapping = filp->f_dentry->d_inode->i_mapping;
struct inode *inode = mapping->host;
unsigned long index, offset;
struct page *cached_page;
int reada_ok;
int error;
int max_readahead = get_max_readahead(inode);
cached_page = NULL;
index = *ppos >> PAGE_CACHE_SHIFT;
offset = *ppos & ~PAGE_CACHE_MASK;
/*
* If the current position is outside the previous read-ahead window,
* we reset the current read-ahead context and set read ahead max to zero
* (will be set to just needed value later),
* otherwise, we assume that the file accesses are sequential enough to
* continue read-ahead.
*/
if (index > filp->f_raend || index + filp->f_rawin < filp->f_raend) {
reada_ok = 0;
filp->f_raend = 0;
filp->f_ralen = 0;
filp->f_ramax = 0;
filp->f_rawin = 0;
} else {
reada_ok = 1;
}
/*
* Adjust the current value of read-ahead max.
* If the read operation stay in the first half page, force no readahead.
* Otherwise try to increase read ahead max just enough to do the read request.
* Then, at least MIN_READAHEAD if read ahead is ok,
* and at most MAX_READAHEAD in all cases.
*/
if (!index && offset + desc->count <= (PAGE_CACHE_SIZE >> 1)) {
filp->f_ramax = 0;
} else {
unsigned long needed;
needed = ((offset + desc->count) >> PAGE_CACHE_SHIFT) + 1;
if (filp->f_ramax < needed)
filp->f_ramax = needed;
if (reada_ok && filp->f_ramax < vm_min_readahead)
filp->f_ramax = vm_min_readahead;
if (filp->f_ramax > max_readahead)
filp->f_ramax = max_readahead;
}
for (;;) {
struct page *page, **hash;
unsigned long end_index, nr, ret;
end_index = inode->i_size >> PAGE_CACHE_SHIFT;
if (index > end_index)
break;
nr = PAGE_CACHE_SIZE;
if (index == end_index) {
nr = inode->i_size & ~PAGE_CACHE_MASK;
if (nr <= offset)
break;
}
nr = nr - offset;
/*
* Try to find the data in the page cache..
*/
hash = page_hash(mapping, index);
spin_lock(&pagecache_lock);
page = __find_page_nolock(mapping, index, *hash);
if (!page)
goto no_cached_page;
found_page:
page_cache_get(page);
spin_unlock(&pagecache_lock);
if (!Page_Uptodate(page))
goto page_not_up_to_date;
generic_file_readahead(reada_ok, filp, inode, page);
page_ok:
/* If users can be writing to this page using arbitrary
* virtual addresses, take care about potential aliasing
* before reading the page on the kernel side.
*/
if (mapping->i_mmap_shared != NULL)
flush_dcache_page(page);
/*
* Mark the page accessed if we read the
* beginning or we just did an lseek.
*/
if (!offset || !filp->f_reada)
mark_page_accessed(page);
/*
* Ok, we have the page, and it's up-to-date, so
* now we can copy it to user space...
*
* The actor routine returns how many bytes were actually used..
* NOTE! This may not be the same as how much of a user buffer
* we filled up (we may be padding etc), so we can only update
* "pos" here (the actor routine has to update the user buffer
* pointers and the remaining count).
*/
ret = actor(desc, page, offset, nr);
offset += ret;
index += offset >> PAGE_CACHE_SHIFT;
offset &= ~PAGE_CACHE_MASK;
page_cache_release(page);
if (ret == nr && desc->count)
continue;
break;
/*
* Ok, the page was not immediately readable, so let's try to read ahead while we're at it..
*/
page_not_up_to_date:
generic_file_readahead(reada_ok, filp, inode, page);
if (Page_Uptodate(page))
goto page_ok;
/* Get exclusive access to the page ... */
lock_page(page);
/* Did it get unhashed before we got the lock? */
if (!page->mapping) {
UnlockPage(page);
page_cache_release(page);
continue;
}
/* Did somebody else fill it already? */
if (Page_Uptodate(page)) {
UnlockPage(page);
goto page_ok;
}
readpage:
/* ... and start the actual read. The read will unlock the page. */
error = mapping->a_ops->readpage(filp, page);
if (!error) {
if (Page_Uptodate(page))
goto page_ok;
/* Again, try some read-ahead while waiting for the page to finish.. */
generic_file_readahead(reada_ok, filp, inode, page);
wait_on_page(page);
if (Page_Uptodate(page))
goto page_ok;
error = -EIO;
}
/* UHHUH! A synchronous read error occurred. Report it */
desc->error = error;
page_cache_release(page);
break;
no_cached_page:
/*
* Ok, it wasn't cached, so we need to create a new
* page..
*
* We get here with the page cache lock held.
*/
if (!cached_page) {
spin_unlock(&pagecache_lock);
cached_page = page_cache_alloc(mapping);
if (!cached_page) {
desc->error = -ENOMEM;
break;
}
/*
* Somebody may have added the page while we
* dropped the page cache lock. Check for that.
*/
spin_lock(&pagecache_lock);
page = __find_page_nolock(mapping, index, *hash);
if (page)
goto found_page;
}
/*
* Ok, add the new page to the hash-queues...
*/
page = cached_page;
__add_to_page_cache(page, mapping, index, hash);
spin_unlock(&pagecache_lock);
lru_cache_add(page);
cached_page = NULL;
goto readpage;
}
*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
filp->f_reada = 1;
if (cached_page)
page_cache_release(cached_page);
UPDATE_ATIME(inode);
}
static ssize_t generic_file_direct_IO(int rw, struct file * filp, char * buf, size_t count, loff_t offset)
{
ssize_t retval;
int new_iobuf, chunk_size, blocksize_mask, blocksize, blocksize_bits, iosize, progress;
struct kiobuf * iobuf;
struct address_space * mapping = filp->f_dentry->d_inode->i_mapping;
struct inode * inode = mapping->host;
new_iobuf = 0;
iobuf = filp->f_iobuf;
if (test_and_set_bit(0, &filp->f_iobuf_lock)) {
/*
* A parallel read/write is using the preallocated iobuf
* so just run slow and allocate a new one.
*/
retval = alloc_kiovec(1, &iobuf);
if (retval)
goto out;
new_iobuf = 1;
}
blocksize = 1 << inode->i_blkbits;
blocksize_bits = inode->i_blkbits;
blocksize_mask = blocksize - 1;
chunk_size = KIO_MAX_ATOMIC_IO << 10;
retval = -EINVAL;
if ((offset & blocksize_mask) || (count & blocksize_mask))
goto out_free;
if (!mapping->a_ops->direct_IO)
goto out_free;
/*
* Flush to disk exclusively the _data_, metadata must remain
* completly asynchronous or performance will go to /dev/null.
*/
retval = filemap_fdatasync(mapping);
if (retval == 0)
retval = fsync_inode_data_buffers(inode);
if (retval == 0)
retval = filemap_fdatawait(mapping);
if (retval < 0)
goto out_free;
progress = retval = 0;
while (count > 0) {
iosize = count;
if (iosize > chunk_size)
iosize = chunk_size;
retval = map_user_kiobuf(rw, iobuf, (unsigned long) buf, iosize);
if (retval)
break;
retval = mapping->a_ops->direct_IO(rw, inode, iobuf, (offset+progress) >> blocksize_bits, blocksize);
if (rw == READ && retval > 0)
mark_dirty_kiobuf(iobuf, retval);
if (retval >= 0) {
count -= retval;
buf += retval;
progress += retval;
}
unmap_kiobuf(iobuf);
if (retval != iosize)
break;
}
if (progress)
retval = progress;
out_free:
if (!new_iobuf)
clear_bit(0, &filp->f_iobuf_lock);
else
free_kiovec(1, &iobuf);
out:
return retval;
}
int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
{
char *kaddr;
unsigned long left, count = desc->count;
if (size > count)
size = count;
kaddr = kmap(page);
left = __copy_to_user(desc->buf, kaddr + offset, size);
kunmap(page);
if (left) {
size -= left;
desc->error = -EFAULT;
}
desc->count = count - size;
desc->written += size;
desc->buf += size;
return size;
}
/*
* This is the "read()" routine for all filesystems
* that can use the page cache directly.
*/
ssize_t generic_file_read(struct file * filp, char * buf, size_t count, loff_t *ppos)
{
ssize_t retval;
if ((ssize_t) count < 0)
return -EINVAL;
if (filp->f_flags & O_DIRECT)
goto o_direct;
retval = -EFAULT;
if (access_ok(VERIFY_WRITE, buf, count)) {
retval = 0;
if (count) {
read_descriptor_t desc;
desc.written = 0;
desc.count = count;
desc.buf = buf;
desc.error = 0;
do_generic_file_read(filp, ppos, &desc, file_read_actor);
retval = desc.written;
if (!retval)
retval = desc.error;
}
}
out:
return retval;
o_direct:
{
loff_t pos = *ppos, size;
struct address_space *mapping = filp->f_dentry->d_inode->i_mapping;
struct inode *inode = mapping->host;
retval = 0;
if (!count)
goto out; /* skip atime */
size = inode->i_size;
if (pos < size) {
if (pos + count > size)
count = size - pos;
retval = generic_file_direct_IO(READ, filp, buf, count, pos);
if (retval > 0)
*ppos = pos + retval;
}
UPDATE_ATIME(filp->f_dentry->d_inode);
goto out;
}
}
static int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset , unsigned long size)
{
ssize_t written;
unsigned long count = desc->count;
struct file *file = (struct file *) desc->buf;
if (size > count)
size = count;
if (file->f_op->sendpage) {
written = file->f_op->sendpage(file, page, offset,
size, &file->f_pos, size<count);
} else {
char *kaddr;
mm_segment_t old_fs;
old_fs = get_fs();
set_fs(KERNEL_DS);
kaddr = kmap(page);
written = file->f_op->write(file, kaddr + offset, size, &file->f_pos);
kunmap(page);
set_fs(old_fs);
}
if (written < 0) {
desc->error = written;
written = 0;
}
desc->count = count - written;
desc->written += written;
return written;
}
asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t *offset, size_t count)
{
ssize_t retval;
struct file * in_file, * out_file;
struct inode * in_inode, * out_inode;
/*
* Get input file, and verify that it is ok..
*/
retval = -EBADF;
in_file = fget(in_fd);
if (!in_file)
goto out;
if (!(in_file->f_mode & FMODE_READ))
goto fput_in;
retval = -EINVAL;
in_inode = in_file->f_dentry->d_inode;
if (!in_inode)
goto fput_in;
if (!in_inode->i_mapping->a_ops->readpage)
goto fput_in;
retval = locks_verify_area(FLOCK_VERIFY_READ, in_inode, in_file, in_file->f_pos, count);
if (retval)
goto fput_in;
/*
* Get output file, and verify that it is ok..
*/
retval = -EBADF;
out_file = fget(out_fd);
if (!out_file)
goto fput_in;
if (!(out_file->f_mode & FMODE_WRITE))
goto fput_out;
retval = -EINVAL;
if (!out_file->f_op || !out_file->f_op->write)
goto fput_out;
out_inode = out_file->f_dentry->d_inode;
retval = locks_verify_area(FLOCK_VERIFY_WRITE, out_inode, out_file, out_file->f_pos, count);
if (retval)
goto fput_out;
retval = 0;
if (count) {
read_descriptor_t desc;
loff_t pos = 0, *ppos;
retval = -EFAULT;
ppos = &in_file->f_pos;
if (offset) {
if (get_user(pos, offset))
goto fput_out;
ppos = &pos;
}
desc.written = 0;
desc.count = count;
desc.buf = (char *) out_file;
desc.error = 0;
do_generic_file_read(in_file, ppos, &desc, file_send_actor);
retval = desc.written;
if (!retval)
retval = desc.error;
if (offset)
put_user(pos, offset);
}
fput_out:
fput(out_file);
fput_in:
fput(in_file);
out:
return retval;
}
static ssize_t do_readahead(struct file *file, unsigned long index, unsigned long nr)
{
struct address_space *mapping = file->f_dentry->d_inode->i_mapping;
unsigned long max;
if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
return -EINVAL;
/* Limit it to the size of the file.. */
max = (mapping->host->i_size + ~PAGE_CACHE_MASK) >> PAGE_CACHE_SHIFT;
if (index > max)
return 0;
max -= index;
if (nr > max)
nr = max;
/* And limit it to a sane percentage of the inactive list.. */
max = nr_inactive_pages / 2;
if (nr > max)
nr = max;
while (nr) {
page_cache_read(file, index);
index++;
nr--;
}
return 0;
}
asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
{
ssize_t ret;
struct file *file;
ret = -EBADF;
file = fget(fd);
if (file) {
if (file->f_mode & FMODE_READ) {
unsigned long start = offset >> PAGE_CACHE_SHIFT;
unsigned long len = (count + ((long)offset & ~PAGE_CACHE_MASK)) >> PAGE_CACHE_SHIFT;
ret = do_readahead(file, start, len);
}
fput(file);
}
return ret;
}
/*
* Read-ahead and flush behind for MADV_SEQUENTIAL areas. Since we are
* sure this is sequential access, we don't need a flexible read-ahead
* window size -- we can always use a large fixed size window.
*/
static void nopage_sequential_readahead(struct vm_area_struct * vma,
unsigned long pgoff, unsigned long filesize)
{
unsigned long ra_window;
ra_window = get_max_readahead(vma->vm_file->f_dentry->d_inode);
ra_window = CLUSTER_OFFSET(ra_window + CLUSTER_PAGES - 1);
/* vm_raend is zero if we haven't read ahead in this area yet. */
if (vma->vm_raend == 0)
vma->vm_raend = vma->vm_pgoff + ra_window;
/*
* If we've just faulted the page half-way through our window,
* then schedule reads for the next window, and release the
* pages in the previous window.
*/
if ((pgoff + (ra_window >> 1)) == vma->vm_raend) {
unsigned long start = vma->vm_pgoff + vma->vm_raend;
unsigned long end = start + ra_window;
if (end > ((vma->vm_end >> PAGE_SHIFT) + vma->vm_pgoff))
end = (vma->vm_end >> PAGE_SHIFT) + vma->vm_pgoff;
if (start > end)
return;
while ((start < end) && (start < filesize)) {
if (read_cluster_nonblocking(vma->vm_file,
start, filesize) < 0)
break;
start += CLUSTER_PAGES;
}
run_task_queue(&tq_disk);
/* if we're far enough past the beginning of this area,
recycle pages that are in the previous window. */
if (vma->vm_raend > (vma->vm_pgoff + ra_window + ra_window)) {
unsigned long window = ra_window << PAGE_SHIFT;
end = vma->vm_start + (vma->vm_raend << PAGE_SHIFT);
end -= window + window;
filemap_sync(vma, end - window, window, MS_INVALIDATE);
}
vma->vm_raend += ra_window;
}
return;
}
/*
* filemap_nopage() is invoked via the vma operations vector for a
* mapped memory region to read in file data during a page fault.
*
* The goto's are kind of ugly, but this streamlines the normal case of having
* it in the page cache, and handles the special cases reasonably without
* having a lot of duplicated code.
*/
struct page * filemap_nopage(struct vm_area_struct * area, unsigned long address, int unused)
{
int error;
struct file *file = area->vm_file;
struct address_space *mapping = file->f_dentry->d_inode->i_mapping;
struct inode *inode = mapping->host;
struct page *page, **hash;
unsigned long size, pgoff, endoff;
pgoff = ((address - area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
endoff = ((area->vm_end - area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
retry_all:
/*
* An external ptracer can access pages that normally aren't
* accessible..
*/
size = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
if ((pgoff >= size) && (area->vm_mm == current->mm))
return NULL;
/* The "size" of the file, as far as mmap is concerned, isn't bigger than the mapping */
if (size > endoff)
size = endoff;
/*
* Do we have something in the page cache already?
*/
hash = page_hash(mapping, pgoff);
retry_find:
page = __find_get_page(mapping, pgoff, hash);
if (!page)
goto no_cached_page;
/*
* Ok, found a page in the page cache, now we need to check
* that it's up-to-date.
*/
if (!Page_Uptodate(page))
goto page_not_uptodate;
success:
/*
* Try read-ahead for sequential areas.
*/
if (VM_SequentialReadHint(area))
nopage_sequential_readahead(area, pgoff, size);
/*
* Found the page and have a reference on it, need to check sharing
* and possibly copy it over to another page..
*/
mark_page_accessed(page);
flush_page_to_ram(page);
return page;
no_cached_page:
/*
* If the requested offset is within our file, try to read a whole
* cluster of pages at once.
*
* Otherwise, we're off the end of a privately mapped file,
* so we need to map a zero page.
*/
if ((pgoff < size) && !VM_RandomReadHint(area))
error = read_cluster_nonblocking(file, pgoff, size);
else
error = page_cache_read(file, pgoff);
/*
* The page we want has now been added to the page cache.
* In the unlikely event that someone removed it in the
* meantime, we'll just come back here and read it again.
*/
if (error >= 0)
goto retry_find;
/*
* An error return from page_cache_read can result if the
* system is low on memory, or a problem occurs while trying
* to schedule I/O.
*/
if (error == -ENOMEM)
return NOPAGE_OOM;
return NULL;
page_not_uptodate:
lock_page(page);
/* Did it get unhashed while we waited for it? */
if (!page->mapping) {
UnlockPage(page);
page_cache_release(page);
goto retry_all;
}
/* Did somebody else get it up-to-date? */
if (Page_Uptodate(page)) {
UnlockPage(page);
goto success;
}
if (!mapping->a_ops->readpage(file, page)) {
wait_on_page(page);
if (Page_Uptodate(page))
goto success;
}
/*
* Umm, take care of errors if the page isn't up-to-date.
* Try to re-read it _once_. We do this synchronously,
* because there really aren't any performance issues here
* and we need to check for errors.
*/
lock_page(page);
/* Somebody truncated the page on us? */
if (!page->mapping) {
UnlockPage(page);
page_cache_release(page);
goto retry_all;
}
/* Somebody else successfully read it in? */
if (Page_Uptodate(page)) {
UnlockPage(page);
goto success;
}
ClearPageError(page);
if (!mapping->a_ops->readpage(file, page)) {
wait_on_page(page);
if (Page_Uptodate(page))
goto success;
}
/*
* Things didn't work out. Return zero to tell the
* mm layer so, possibly freeing the page cache page first.
*/
page_cache_release(page);
return NULL;
}
/* Called with mm->page_table_lock held to protect against other
* threads/the swapper from ripping pte's out from under us.
*/
static inline int filemap_sync_pte(pte_t * ptep, struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
{
pte_t pte = *ptep;
if (pte_present(pte)) {
struct page *page = pte_page(pte);
if (VALID_PAGE(page) && !PageReserved(page) && ptep_test_and_clear_dirty(ptep)) {
flush_tlb_page(vma, address);
set_page_dirty(page);
}
}
return 0;
}
static inline int filemap_sync_pte_range(pmd_t * pmd,
unsigned long address, unsigned long size,
struct vm_area_struct *vma, unsigned long offset, unsigned int flags)
{
pte_t * pte;
unsigned long end;
int error;
if (pmd_none(*pmd))
return 0;
if (pmd_bad(*pmd)) {
pmd_ERROR(*pmd);
pmd_clear(pmd);
return 0;
}
pte = pte_offset(pmd, address);
offset += address & PMD_MASK;
address &= ~PMD_MASK;
end = address + size;
if (end > PMD_SIZE)
end = PMD_SIZE;
error = 0;
do {
error |= filemap_sync_pte(pte, vma, address + offset, flags);
address += PAGE_SIZE;
pte++;
} while (address && (address < end));
return error;
}
static inline int filemap_sync_pmd_range(pgd_t * pgd,
unsigned long address, unsigned long size,
struct vm_area_struct *vma, unsigned int flags)
{
pmd_t * pmd;
unsigned long offset, end;
int error;
if (pgd_none(*pgd))
return 0;
if (pgd_bad(*pgd)) {
pgd_ERROR(*pgd);
pgd_clear(pgd);
return 0;
}
pmd = pmd_offset(pgd, address);
offset = address & PGDIR_MASK;
address &= ~PGDIR_MASK;
end = address + size;
if (end > PGDIR_SIZE)
end = PGDIR_SIZE;
error = 0;
do {
error |= filemap_sync_pte_range(pmd, address, end - address, vma, offset, flags);
address = (address + PMD_SIZE) & PMD_MASK;
pmd++;
} while (address && (address < end));
return error;
}
int filemap_sync(struct vm_area_struct * vma, unsigned long address,
size_t size, unsigned int flags)
{
pgd_t * dir;
unsigned long end = address + size;
int error = 0;
/* Aquire the lock early; it may be possible to avoid dropping
* and reaquiring it repeatedly.
*/
spin_lock(&vma->vm_mm->page_table_lock);
dir = pgd_offset(vma->vm_mm, address);
flush_cache_range(vma->vm_mm, end - size, end);
if (address >= end)
BUG();
do {
error |= filemap_sync_pmd_range(dir, address, end - address, vma, flags);
address = (address + PGDIR_SIZE) & PGDIR_MASK;
dir++;
} while (address && (address < end));
flush_tlb_range(vma->vm_mm, end - size, end);
spin_unlock(&vma->vm_mm->page_table_lock);
return error;
}
static struct vm_operations_struct generic_file_vm_ops = {
nopage: filemap_nopage,
};
/* This is used for a general mmap of a disk file */
int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
{
struct address_space *mapping = file->f_dentry->d_inode->i_mapping;
struct inode *inode = mapping->host;
if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) {
if (!mapping->a_ops->writepage)
return -EINVAL;
}
if (!mapping->a_ops->readpage)
return -ENOEXEC;
UPDATE_ATIME(inode);
vma->vm_ops = &generic_file_vm_ops;
return 0;
}
/*
* The msync() system call.
*/
/*
* MS_SYNC syncs the entire file - including mappings.
*
* MS_ASYNC initiates writeout of just the dirty mapped data.
* This provides no guarantee of file integrity - things like indirect
* blocks may not have started writeout. MS_ASYNC is primarily useful
* where the application knows that it has finished with the data and
* wishes to intelligently schedule its own I/O traffic.
*/
static int msync_interval(struct vm_area_struct * vma,
unsigned long start, unsigned long end, int flags)
{
int ret = 0;
struct file * file = vma->vm_file;
if (file && (vma->vm_flags & VM_SHARED)) {
ret = filemap_sync(vma, start, end-start, flags);
if (!ret && (flags & (MS_SYNC|MS_ASYNC))) {
struct inode * inode = file->f_dentry->d_inode;
down(&inode->i_sem);
ret = filemap_fdatasync(inode->i_mapping);
if (flags & MS_SYNC) {
int err;
if (file->f_op && file->f_op->fsync) {
err = file->f_op->fsync(file, file->f_dentry, 1);
if (err && !ret)
ret = err;
}
err = filemap_fdatawait(inode->i_mapping);
if (err && !ret)
ret = err;
}
up(&inode->i_sem);
}
}
return ret;
}
asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
{
unsigned long end;
struct vm_area_struct * vma;
int unmapped_error, error = -EINVAL;
down_read(¤t->mm->mmap_sem);
if (start & ~PAGE_MASK)
goto out;
len = (len + ~PAGE_MASK) & PAGE_MASK;
end = start + len;
if (end < start)
goto out;
if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
goto out;
error = 0;
if (end == start)
goto out;
/*
* If the interval [start,end) covers some unmapped address ranges,
* just ignore them, but return -EFAULT at the end.
*/
vma = find_vma(current->mm, start);
unmapped_error = 0;
for (;;) {
/* Still start < end. */
error = -EFAULT;
if (!vma)
goto out;
/* Here start < vma->vm_end. */
if (start < vma->vm_start) {
unmapped_error = -EFAULT;
start = vma->vm_start;
}
/* Here vma->vm_start <= start < vma->vm_end. */
if (end <= vma->vm_end) {
if (start < end) {
error = msync_interval(vma, start, end, flags);
if (error)
goto out;
}
error = unmapped_error;
goto out;
}
/* Here vma->vm_start <= start < vma->vm_end < end. */
error = msync_interval(vma, start, vma->vm_end, flags);
if (error)
goto out;
start = vma->vm_end;
vma = vma->vm_next;
}
out:
up_read(¤t->mm->mmap_sem);
return error;
}
static inline void setup_read_behavior(struct vm_area_struct * vma,
int behavior)
{
VM_ClearReadHint(vma);
switch(behavior) {
case MADV_SEQUENTIAL:
vma->vm_flags |= VM_SEQ_READ;
break;
case MADV_RANDOM:
vma->vm_flags |= VM_RAND_READ;
break;
default:
break;
}
return;
}
static long madvise_fixup_start(struct vm_area_struct * vma,
unsigned long end, int behavior)
{
struct vm_area_struct * n;
struct mm_struct * mm = vma->vm_mm;
n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!n)
return -EAGAIN;
*n = *vma;
n->vm_end = end;
setup_read_behavior(n, behavior);
n->vm_raend = 0;
if (n->vm_file)
get_file(n->vm_file);
if (n->vm_ops && n->vm_ops->open)
n->vm_ops->open(n);
vma->vm_pgoff += (end - vma->vm_start) >> PAGE_SHIFT;
lock_vma_mappings(vma);
spin_lock(&mm->page_table_lock);
vma->vm_start = end;
__insert_vm_struct(mm, n);
spin_unlock(&mm->page_table_lock);
unlock_vma_mappings(vma);
return 0;
}
static long madvise_fixup_end(struct vm_area_struct * vma,
unsigned long start, int behavior)
{
struct vm_area_struct * n;
struct mm_struct * mm = vma->vm_mm;
n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!n)
return -EAGAIN;
*n = *vma;
n->vm_start = start;
n->vm_pgoff += (n->vm_start - vma->vm_start) >> PAGE_SHIFT;
setup_read_behavior(n, behavior);
n->vm_raend = 0;
if (n->vm_file)
get_file(n->vm_file);
if (n->vm_ops && n->vm_ops->open)
n->vm_ops->open(n);
lock_vma_mappings(vma);
spin_lock(&mm->page_table_lock);
vma->vm_end = start;
__insert_vm_struct(mm, n);
spin_unlock(&mm->page_table_lock);
unlock_vma_mappings(vma);
return 0;
}
static long madvise_fixup_middle(struct vm_area_struct * vma,
unsigned long start, unsigned long end, int behavior)
{
struct vm_area_struct * left, * right;
struct mm_struct * mm = vma->vm_mm;
left = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!left)
return -EAGAIN;
right = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!right) {
kmem_cache_free(vm_area_cachep, left);
return -EAGAIN;
}
*left = *vma;
*right = *vma;
left->vm_end = start;
right->vm_start = end;
right->vm_pgoff += (right->vm_start - left->vm_start) >> PAGE_SHIFT;
left->vm_raend = 0;
right->vm_raend = 0;
if (vma->vm_file)
atomic_add(2, &vma->vm_file->f_count);
if (vma->vm_ops && vma->vm_ops->open) {
vma->vm_ops->open(left);
vma->vm_ops->open(right);
}
vma->vm_pgoff += (start - vma->vm_start) >> PAGE_SHIFT;
vma->vm_raend = 0;
lock_vma_mappings(vma);
spin_lock(&mm->page_table_lock);
vma->vm_start = start;
vma->vm_end = end;
setup_read_behavior(vma, behavior);
__insert_vm_struct(mm, left);
__insert_vm_struct(mm, right);
spin_unlock(&mm->page_table_lock);
unlock_vma_mappings(vma);
return 0;
}
/*
* We can potentially split a vm area into separate
* areas, each area with its own behavior.
*/
static long madvise_behavior(struct vm_area_struct * vma,
unsigned long start, unsigned long end, int behavior)
{
int error = 0;
/* This caps the number of vma's this process can own */
if (vma->vm_mm->map_count > MAX_MAP_COUNT)
return -ENOMEM;
if (start == vma->vm_start) {
if (end == vma->vm_end) {
setup_read_behavior(vma, behavior);
vma->vm_raend = 0;
} else
error = madvise_fixup_start(vma, end, behavior);
} else {
if (end == vma->vm_end)
error = madvise_fixup_end(vma, start, behavior);
else
error = madvise_fixup_middle(vma, start, end, behavior);
}
return error;
}
/*
* Schedule all required I/O operations, then run the disk queue
* to make sure they are started. Do not wait for completion.
*/
static long madvise_willneed(struct vm_area_struct * vma,
unsigned long start, unsigned long end)
{
long error = -EBADF;
struct file * file;
unsigned long size, rlim_rss;
/* Doesn't work if there's no mapped file. */
if (!vma->vm_file)
return error;
file = vma->vm_file;
size = (file->f_dentry->d_inode->i_size + PAGE_CACHE_SIZE - 1) >>
PAGE_CACHE_SHIFT;
start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
if (end > vma->vm_end)
end = vma->vm_end;
end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
/* Make sure this doesn't exceed the process's max rss. */
error = -EIO;
rlim_rss = current->rlim ? current->rlim[RLIMIT_RSS].rlim_cur :
LONG_MAX; /* default: see resource.h */
if ((vma->vm_mm->rss + (end - start)) > rlim_rss)
return error;
/* round to cluster boundaries if this isn't a "random" area. */
if (!VM_RandomReadHint(vma)) {
start = CLUSTER_OFFSET(start);
end = CLUSTER_OFFSET(end + CLUSTER_PAGES - 1);
while ((start < end) && (start < size)) {
error = read_cluster_nonblocking(file, start, size);
start += CLUSTER_PAGES;
if (error < 0)
break;
}
} else {
while ((start < end) && (start < size)) {
error = page_cache_read(file, start);
start++;
if (error < 0)
break;
}
}
/* Don't wait for someone else to push these requests. */
run_task_queue(&tq_disk);
return error;
}
/*
* Application no longer needs these pages. If the pages are dirty,
* it's OK to just throw them away. The app will be more careful about
* data it wants to keep. Be sure to free swap resources too. The
* zap_page_range call sets things up for refill_inactive to actually free
* these pages later if no one else has touched them in the meantime,
* although we could add these pages to a global reuse list for
* refill_inactive to pick up before reclaiming other pages.
*
* NB: This interface discards data rather than pushes it out to swap,
* as some implementations do. This has performance implications for
* applications like large transactional databases which want to discard
* pages in anonymous maps after committing to backing store the data
* that was kept in them. There is no reason to write this data out to
* the swap area if the application is discarding it.
*
* An interface that causes the system to free clean pages and flush
* dirty pages is already available as msync(MS_INVALIDATE).
*/
static long madvise_dontneed(struct vm_area_struct * vma,
unsigned long start, unsigned long end)
{
if (vma->vm_flags & VM_LOCKED)
return -EINVAL;
zap_page_range(vma->vm_mm, start, end - start);
return 0;
}
static long madvise_vma(struct vm_area_struct * vma, unsigned long start,
unsigned long end, int behavior)
{
long error = -EBADF;
switch (behavior) {
case MADV_NORMAL:
case MADV_SEQUENTIAL:
case MADV_RANDOM:
error = madvise_behavior(vma, start, end, behavior);
break;
case MADV_WILLNEED:
error = madvise_willneed(vma, start, end);
break;
case MADV_DONTNEED:
error = madvise_dontneed(vma, start, end);
break;
default:
error = -EINVAL;
break;
}
return error;
}
/*
* The madvise(2) system call.
*
* Applications can use madvise() to advise the kernel how it should
* handle paging I/O in this VM area. The idea is to help the kernel
* use appropriate read-ahead and caching techniques. The information
* provided is advisory only, and can be safely disregarded by the
* kernel without affecting the correct operation of the application.
*
* behavior values:
* MADV_NORMAL - the default behavior is to read clusters. This
* results in some read-ahead and read-behind.
* MADV_RANDOM - the system should read the minimum amount of data
* on any access, since it is unlikely that the appli-
* cation will need more than what it asks for.
* MADV_SEQUENTIAL - pages in the given range will probably be accessed
* once, so they can be aggressively read ahead, and
* can be freed soon after they are accessed.
* MADV_WILLNEED - the application is notifying the system to read
* some pages ahead.
* MADV_DONTNEED - the application is finished with the given range,
* so the kernel can free resources associated with it.
*
* return values:
* zero - success
* -EINVAL - start + len < 0, start is not page-aligned,
* "behavior" is not a valid value, or application
* is attempting to release locked or shared pages.
* -ENOMEM - addresses in the specified range are not currently
* mapped, or are outside the AS of the process.
* -EIO - an I/O error occurred while paging in data.
* -EBADF - map exists, but area maps something that isn't a file.
* -EAGAIN - a kernel resource was temporarily unavailable.
*/
asmlinkage long sys_madvise(unsigned long start, size_t len, int behavior)
{
unsigned long end;
struct vm_area_struct * vma;
int unmapped_error = 0;
int error = -EINVAL;
down_write(¤t->mm->mmap_sem);
if (start & ~PAGE_MASK)
goto out;
len = (len + ~PAGE_MASK) & PAGE_MASK;
end = start + len;
if (end < start)
goto out;
error = 0;
if (end == start)
goto out;
/*
* If the interval [start,end) covers some unmapped address
* ranges, just ignore them, but return -ENOMEM at the end.
*/
vma = find_vma(current->mm, start);
for (;;) {
/* Still start < end. */
error = -ENOMEM;
if (!vma)
goto out;
/* Here start < vma->vm_end. */
if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
}
/* Here vma->vm_start <= start < vma->vm_end. */
if (end <= vma->vm_end) {
if (start < end) {
error = madvise_vma(vma, start, end,
behavior);
if (error)
goto out;
}
error = unmapped_error;
goto out;
}
/* Here vma->vm_start <= start < vma->vm_end < end. */
error = madvise_vma(vma, start, vma->vm_end, behavior);
if (error)
goto out;
start = vma->vm_end;
vma = vma->vm_next;
}
out:
up_write(¤t->mm->mmap_sem);
return error;
}
/*
* Later we can get more picky about what "in core" means precisely.
* For now, simply check to see if the page is in the page cache,
* and is up to date; i.e. that no page-in operation would be required
* at this time if an application were to map and access this page.
*/
static unsigned char mincore_page(struct vm_area_struct * vma,
unsigned long pgoff)
{
unsigned char present = 0;
struct address_space * as = vma->vm_file->f_dentry->d_inode->i_mapping;
struct page * page, ** hash = page_hash(as, pgoff);
spin_lock(&pagecache_lock);
page = __find_page_nolock(as, pgoff, *hash);
if ((page) && (Page_Uptodate(page)))
present = 1;
spin_unlock(&pagecache_lock);
return present;
}
static long mincore_vma(struct vm_area_struct * vma,
unsigned long start, unsigned long end, unsigned char * vec)
{
long error, i, remaining;
unsigned char * tmp;
error = -ENOMEM;
if (!vma->vm_file)
return error;
start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
if (end > vma->vm_end)
end = vma->vm_end;
end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
error = -EAGAIN;
tmp = (unsigned char *) __get_free_page(GFP_KERNEL);
if (!tmp)
return error;
/* (end - start) is # of pages, and also # of bytes in "vec */
remaining = (end - start),
error = 0;
for (i = 0; remaining > 0; remaining -= PAGE_SIZE, i++) {
int j = 0;
long thispiece = (remaining < PAGE_SIZE) ?
remaining : PAGE_SIZE;
while (j < thispiece)
tmp[j++] = mincore_page(vma, start++);
if (copy_to_user(vec + PAGE_SIZE * i, tmp, thispiece)) {
error = -EFAULT;
break;
}
}
free_page((unsigned long) tmp);
return error;
}
/*
* The mincore(2) system call.
*
* mincore() returns the memory residency status of the pages in the
* current process's address space specified by [addr, addr + len).
* The status is returned in a vector of bytes. The least significant
* bit of each byte is 1 if the referenced page is in memory, otherwise
* it is zero.
*
* Because the status of a page can change after mincore() checks it
* but before it returns to the application, the returned vector may
* contain stale information. Only locked pages are guaranteed to
* remain in memory.
*
* return values:
* zero - success
* -EFAULT - vec points to an illegal address
* -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE,
* or len has a nonpositive value
* -ENOMEM - Addresses in the range [addr, addr + len] are
* invalid for the address space of this process, or
* specify one or more pages which are not currently
* mapped
* -EAGAIN - A kernel resource was temporarily unavailable.
*/
asmlinkage long sys_mincore(unsigned long start, size_t len,
unsigned char * vec)
{
int index = 0;
unsigned long end;
struct vm_area_struct * vma;
int unmapped_error = 0;
long error = -EINVAL;
down_read(¤t->mm->mmap_sem);
if (start & ~PAGE_CACHE_MASK)
goto out;
len = (len + ~PAGE_CACHE_MASK) & PAGE_CACHE_MASK;
end = start + len;
if (end < start)
goto out;
error = 0;
if (end == start)
goto out;
/*
* If the interval [start,end) covers some unmapped address
* ranges, just ignore them, but return -ENOMEM at the end.
*/
vma = find_vma(current->mm, start);
for (;;) {
/* Still start < end. */
error = -ENOMEM;
if (!vma)
goto out;
/* Here start < vma->vm_end. */
if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
}
/* Here vma->vm_start <= start < vma->vm_end. */
if (end <= vma->vm_end) {
if (start < end) {
error = mincore_vma(vma, start, end,
&vec[index]);
if (error)
goto out;
}
error = unmapped_error;
goto out;
}
/* Here vma->vm_start <= start < vma->vm_end < end. */
error = mincore_vma(vma, start, vma->vm_end, &vec[index]);
if (error)
goto out;
index += (vma->vm_end - start) >> PAGE_CACHE_SHIFT;
start = vma->vm_end;
vma = vma->vm_next;
}
out:
up_read(¤t->mm->mmap_sem);
return error;
}
static inline
struct page *__read_cache_page(struct address_space *mapping,
unsigned long index,
int (*filler)(void *,struct page*),
void *data)
{
struct page **hash = page_hash(mapping, index);
struct page *page, *cached_page = NULL;
int err;
repeat:
page = __find_get_page(mapping, index, hash);
if (!page) {
if (!cached_page) {
cached_page = page_cache_alloc(mapping);
if (!cached_page)
return ERR_PTR(-ENOMEM);
}
page = cached_page;
if (add_to_page_cache_unique(page, mapping, index, hash))
goto repeat;
cached_page = NULL;
err = filler(data, page);
if (err < 0) {
page_cache_release(page);
page = ERR_PTR(err);
}
}
if (cached_page)
page_cache_release(cached_page);
return page;
}
/*
* Read into the page cache. If a page already exists,
* and Page_Uptodate() is not set, try to fill the page.
*/
struct page *read_cache_page(struct address_space *mapping,
unsigned long index,
int (*filler)(void *,struct page*),
void *data)
{
struct page *page;
int err;
retry:
page = __read_cache_page(mapping, index, filler, data);
if (IS_ERR(page))
goto out;
mark_page_accessed(page);
if (Page_Uptodate(page))
goto out;
lock_page(page);
if (!page->mapping) {
UnlockPage(page);
page_cache_release(page);
goto retry;
}
if (Page_Uptodate(page)) {
UnlockPage(page);
goto out;
}
err = filler(data, page);
if (err < 0) {
page_cache_release(page);
page = ERR_PTR(err);
}
out:
return page;
}
static inline struct page * __grab_cache_page(struct address_space *mapping,
unsigned long index, struct page **cached_page)
{
struct page *page, **hash = page_hash(mapping, index);
repeat:
page = __find_lock_page(mapping, index, hash);
if (!page) {
if (!*cached_page) {
*cached_page = page_cache_alloc(mapping);
if (!*cached_page)
return NULL;
}
page = *cached_page;
if (add_to_page_cache_unique(page, mapping, index, hash))
goto repeat;
*cached_page = NULL;
}
return page;
}
inline void remove_suid(struct inode *inode)
{
unsigned int mode;
/* set S_IGID if S_IXGRP is set, and always set S_ISUID */
mode = (inode->i_mode & S_IXGRP)*(S_ISGID/S_IXGRP) | S_ISUID;
/* was any of the uid bits set? */
mode &= inode->i_mode;
if (mode && !capable(CAP_FSETID)) {
inode->i_mode &= ~mode;
mark_inode_dirty(inode);
}
}
/*
* Write to a file through the page cache.
*
* We currently put everything into the page cache prior to writing it.
* This is not a problem when writing full pages. With partial pages,
* however, we first have to read the data into the cache, then
* dirty the page, and finally schedule it for writing. Alternatively, we
* could write-through just the portion of data that would go into that
* page, but that would kill performance for applications that write data
* line by line, and it's prone to race conditions.
*
* Note that this routine doesn't try to keep track of dirty pages. Each
* file system has to do this all by itself, unfortunately.
* okir@monad.swb.de
*/
ssize_t
generic_file_write(struct file *file,const char *buf,size_t count, loff_t *ppos)
{
struct address_space *mapping = file->f_dentry->d_inode->i_mapping;
struct inode *inode = mapping->host;
unsigned long limit = current->rlim[RLIMIT_FSIZE].rlim_cur;
loff_t pos;
struct page *page, *cached_page;
ssize_t written;
long status = 0;
int err;
unsigned bytes;
if ((ssize_t) count < 0)
return -EINVAL;
if (!access_ok(VERIFY_READ, buf, count))
return -EFAULT;
cached_page = NULL;
down(&inode->i_sem);
pos = *ppos;
err = -EINVAL;
if (pos < 0)
goto out;
err = file->f_error;
if (err) {
file->f_error = 0;
goto out;
}
written = 0;
/* FIXME: this is for backwards compatibility with 2.4 */
if (!S_ISBLK(inode->i_mode) && file->f_flags & O_APPEND)
pos = inode->i_size;
/*
* Check whether we've reached the file size limit.
*/
err = -EFBIG;
if (limit != RLIM_INFINITY) {
if (pos >= limit) {
send_sig(SIGXFSZ, current, 0);
goto out;
}
if (pos > 0xFFFFFFFFULL || count > limit - (u32)pos) {
/* send_sig(SIGXFSZ, current, 0); */
count = limit - (u32)pos;
}
}
/*
* LFS rule
*/
if ( pos + count > MAX_NON_LFS && !(file->f_flags&O_LARGEFILE)) {
if (pos >= MAX_NON_LFS) {
send_sig(SIGXFSZ, current, 0);
goto out;
}
if (count > MAX_NON_LFS - (u32)pos) {
/* send_sig(SIGXFSZ, current, 0); */
count = MAX_NON_LFS - (u32)pos;
}
}
/*
* Are we about to exceed the fs block limit ?
*
* If we have written data it becomes a short write
* If we have exceeded without writing data we send
* a signal and give them an EFBIG.
*
* Linus frestrict idea will clean these up nicely..
*/
if (!S_ISBLK(inode->i_mode)) {
if (pos >= inode->i_sb->s_maxbytes)
{
if (count || pos > inode->i_sb->s_maxbytes) {
send_sig(SIGXFSZ, current, 0);
err = -EFBIG;
goto out;
}
/* zero-length writes at ->s_maxbytes are OK */
}
if (pos + count > inode->i_sb->s_maxbytes)
count = inode->i_sb->s_maxbytes - pos;
} else {
if (is_read_only(inode->i_rdev)) {
err = -EPERM;
goto out;
}
if (pos >= inode->i_size) {
if (count || pos > inode->i_size) {
err = -ENOSPC;
goto out;
}
}
if (pos + count > inode->i_size)
count = inode->i_size - pos;
}
err = 0;
if (count == 0)
goto out;
remove_suid(inode);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
mark_inode_dirty_sync(inode);
if (file->f_flags & O_DIRECT)
goto o_direct;
do {
unsigned long index, offset;
long page_fault;
char *kaddr;
/*
* Try to find the page in the cache. If it isn't there,
* allocate a free page.
*/
offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
index = pos >> PAGE_CACHE_SHIFT;
bytes = PAGE_CACHE_SIZE - offset;
if (bytes > count)
bytes = count;
/*
* Bring in the user page that we will copy from _first_.
* Otherwise there's a nasty deadlock on copying from the
* same page as we're writing to, without it being marked
* up-to-date.
*/
{ volatile unsigned char dummy;
__get_user(dummy, buf);
__get_user(dummy, buf+bytes-1);
}
status = -ENOMEM; /* we'll assign it later anyway */
page = __grab_cache_page(mapping, index, &cached_page);
if (!page)
break;
/* We have exclusive IO access to the page.. */
if (!PageLocked(page)) {
PAGE_BUG(page);
}
kaddr = kmap(page);
status = mapping->a_ops->prepare_write(file, page, offset, offset+bytes);
if (status)
goto sync_failure;
page_fault = __copy_from_user(kaddr+offset, buf, bytes);
flush_dcache_page(page);
status = mapping->a_ops->commit_write(file, page, offset, offset+bytes);
if (page_fault)
goto fail_write;
if (!status)
status = bytes;
if (status >= 0) {
written += status;
count -= status;
pos += status;
buf += status;
}
unlock:
kunmap(page);
/* Mark it unlocked again and drop the page.. */
SetPageReferenced(page);
UnlockPage(page);
page_cache_release(page);
if (status < 0)
break;
} while (count);
done:
*ppos = pos;
if (cached_page)
page_cache_release(cached_page);
/* For now, when the user asks for O_SYNC, we'll actually
* provide O_DSYNC. */
if (status >= 0) {
if ((file->f_flags & O_SYNC) || IS_SYNC(inode))
status = generic_osync_inode(inode, OSYNC_METADATA|OSYNC_DATA);
}
out_status:
err = written ? written : status;
out:
up(&inode->i_sem);
return err;
fail_write:
status = -EFAULT;
goto unlock;
sync_failure:
/*
* If blocksize < pagesize, prepare_write() may have instantiated a
* few blocks outside i_size. Trim these off again.
*/
kunmap(page);
UnlockPage(page);
page_cache_release(page);
if (pos + bytes > inode->i_size)
vmtruncate(inode, inode->i_size);
goto done;
o_direct:
written = generic_file_direct_IO(WRITE, file, (char *) buf, count, pos);
if (written > 0) {
loff_t end = pos + written;
if (end > inode->i_size && !S_ISBLK(inode->i_mode)) {
inode->i_size = end;
mark_inode_dirty(inode);
}
*ppos = end;
invalidate_inode_pages2(mapping);
}
/*
* Sync the fs metadata but not the minor inode changes and
* of course not the data as we did direct DMA for the IO.
*/
if (written >= 0 && file->f_flags & O_SYNC)
status = generic_osync_inode(inode, OSYNC_METADATA);
goto out_status;
}
void __init page_cache_init(unsigned long mempages)
{
unsigned long htable_size, order;
htable_size = mempages;
htable_size *= sizeof(struct page *);
for(order = 0; (PAGE_SIZE << order) < htable_size; order++)
;
do {
unsigned long tmp = (PAGE_SIZE << order) / sizeof(struct page *);
page_hash_bits = 0;
while((tmp >>= 1UL) != 0UL)
page_hash_bits++;
page_hash_table = (struct page **)
__get_free_pages(GFP_ATOMIC, order);
} while(page_hash_table == NULL && --order > 0);
printk("Page-cache hash table entries: %d (order: %ld, %ld bytes)\n",
(1 << page_hash_bits), order, (PAGE_SIZE << order));
if (!page_hash_table)
panic("Failed to allocate page hash table\n");
memset((void *)page_hash_table, 0, PAGE_HASH_SIZE * sizeof(struct page *));
}
|