/*
* 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/malloc.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/slab.h>
#include <linux/init.h>
#include <linux/mm.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;
spinlock_t pagecache_lock = SPIN_LOCK_UNLOCKED;
/*
* NOTE: to avoid deadlocking you must never acquire the pagecache_lock with
* the pagemap_lru_lock held.
*/
spinlock_t pagemap_lru_lock = SPIN_LOCK_UNLOCKED;
#define CLUSTER_PAGES (1 << page_cluster)
#define CLUSTER_OFFSET(x) (((x) >> page_cluster) << page_cluster)
58 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;
65 if (next)
next->pprev_hash = &page->next_hash;
67 if (page->buffers)
68 PAGE_BUG(page);
atomic_inc(&page_cache_size);
}
72 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;
}
81 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;
}
90 static inline void remove_page_from_hash_queue(struct page * page)
{
struct page *next = page->next_hash;
struct page **pprev = page->pprev_hash;
95 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.
*/
107 void __remove_inode_page(struct page *page)
{
109 if (PageDirty(page)) BUG();
remove_page_from_inode_queue(page);
remove_page_from_hash_queue(page);
page->mapping = NULL;
}
115 void remove_inode_page(struct page *page)
{
117 if (!PageLocked(page))
118 PAGE_BUG(page);
spin_lock(&pagecache_lock);
__remove_inode_page(page);
122 spin_unlock(&pagecache_lock);
}
125 static inline int sync_page(struct page *page)
{
struct address_space *mapping = page->mapping;
129 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
130 return mapping->a_ops->sync_page(page);
131 return 0;
}
/*
* Add a page to the dirty page list.
*/
137 void __set_page_dirty(struct page *page)
{
struct address_space *mapping = page->mapping;
spin_lock(&pagecache_lock);
list_del(&page->list);
list_add(&page->list, &mapping->dirty_pages);
144 spin_unlock(&pagecache_lock);
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.
*/
157 void invalidate_inode_pages(struct inode * inode)
{
struct list_head *head, *curr;
struct page * page;
head = &inode->i_mapping->clean_pages;
spin_lock(&pagecache_lock);
spin_lock(&pagemap_lru_lock);
curr = head->next;
168 while (curr != head) {
page = list_entry(curr, struct page, list);
curr = curr->next;
/* We cannot invalidate something in use.. */
173 if (page_count(page) != 1)
174 continue;
/* ..or dirty.. */
177 if (PageDirty(page))
178 continue;
/* ..or locked */
181 if (TryLockPage(page))
182 continue;
__lru_cache_del(page);
__remove_inode_page(page);
186 UnlockPage(page);
page_cache_release(page);
}
190 spin_unlock(&pagemap_lru_lock);
191 spin_unlock(&pagecache_lock);
}
194 static inline void truncate_partial_page(struct page *page, unsigned partial)
{
memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
198 if (page->buffers)
block_flushpage(page, partial);
}
203 static inline void truncate_complete_page(struct page *page)
{
/* Leave it on the LRU if it gets converted into anonymous buffers */
206 if (!page->buffers || block_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 *));
223 static int truncate_list_pages(struct list_head *head, unsigned long start, unsigned *partial)
{
struct list_head *curr;
struct page * page;
curr = head->next;
229 while (curr != head) {
unsigned long offset;
page = list_entry(curr, struct page, list);
curr = curr->next;
offset = page->index;
/* Is one of the pages to truncate? */
237 if ((offset >= start) || (*partial && (offset + 1) == start)) {
238 if (TryLockPage(page)) {
page_cache_get(page);
240 spin_unlock(&pagecache_lock);
wait_on_page(page);
page_cache_release(page);
243 return 1;
}
page_cache_get(page);
246 spin_unlock(&pagecache_lock);
248 if (*partial && (offset + 1) == start) {
truncate_partial_page(page, *partial);
*partial = 0;
251 } else
truncate_complete_page(page);
254 UnlockPage(page);
page_cache_release(page);
256 return 1;
}
}
259 return 0;
}
/**
* 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.
*/
272 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);
repeat:
spin_lock(&pagecache_lock);
279 if (truncate_list_pages(&mapping->clean_pages, start, &partial))
280 goto repeat;
281 if (truncate_list_pages(&mapping->dirty_pages, start, &partial))
282 goto repeat;
283 if (truncate_list_pages(&mapping->locked_pages, start, &partial))
284 goto repeat;
285 spin_unlock(&pagecache_lock);
}
288 static inline struct page * __find_page_nolock(struct address_space *mapping, unsigned long offset, struct page *page)
{
290 goto inside;
292 for (;;) {
page = page->next_hash;
inside:
295 if (!page)
296 goto not_found;
297 if (page->mapping != mapping)
298 continue;
299 if (page->index == offset)
300 break;
}
/*
* Touching the page may move it to the active list.
* If we end up with too few inactive pages, we wake
* up kswapd.
*/
age_page_up(page);
308 if (inactive_shortage() > inactive_target / 2 && free_shortage())
wakeup_kswapd(0);
not_found:
311 return page;
}
/*
* By the time this is called, the page is locked and
* we don't have to worry about any races any more.
*
* Start the IO..
*/
320 static int writeout_one_page(struct page *page)
{
struct buffer_head *bh, *head = page->buffers;
bh = head;
325 do {
326 if (buffer_locked(bh) || !buffer_dirty(bh) || !buffer_uptodate(bh))
327 continue;
bh->b_flushtime = jiffies;
ll_rw_block(WRITE, 1, &bh);
331 } while ((bh = bh->b_this_page) != head);
332 return 0;
}
335 static int waitfor_one_page(struct page *page)
{
int error = 0;
struct buffer_head *bh, *head = page->buffers;
bh = head;
341 do {
wait_on_buffer(bh);
343 if (buffer_req(bh) && !buffer_uptodate(bh))
error = -EIO;
345 } while ((bh = bh->b_this_page) != head);
346 return error;
}
349 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;
357 while (curr != head) {
page = list_entry(curr, struct page, list);
curr = curr->next;
360 if (!page->buffers)
361 continue;
362 if (page->index >= end)
363 continue;
364 if (page->index < start)
365 continue;
page_cache_get(page);
368 spin_unlock(&pagecache_lock);
lock_page(page);
/* The buffers could have been free'd while we waited for the page lock */
372 if (page->buffers)
retval |= fn(page);
375 UnlockPage(page);
spin_lock(&pagecache_lock);
curr = page->list.next;
page_cache_release(page);
}
380 spin_unlock(&pagecache_lock);
382 return retval;
}
/*
* Two-stage data sync: first start the IO, then go back and
* collect the information..
*/
389 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, writeout_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);
403 return retval;
}
/**
* filemap_fdatasync - walk the list of dirty pages of the given address space
* and writepage() all of them.
*
* @mapping: address space structure to write
*
*/
413 void filemap_fdatasync(struct address_space * mapping)
{
int (*writepage)(struct page *) = mapping->a_ops->writepage;
spin_lock(&pagecache_lock);
419 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);
425 if (!PageDirty(page))
426 continue;
page_cache_get(page);
429 spin_unlock(&pagecache_lock);
lock_page(page);
433 if (PageDirty(page)) {
ClearPageDirty(page);
writepage(page);
436 } else
437 UnlockPage(page);
page_cache_release(page);
spin_lock(&pagecache_lock);
}
442 spin_unlock(&pagecache_lock);
}
/**
* 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
*
*/
452 void filemap_fdatawait(struct address_space * mapping)
{
spin_lock(&pagecache_lock);
456 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);
462 if (!PageLocked(page))
463 continue;
page_cache_get(page);
466 spin_unlock(&pagecache_lock);
___wait_on_page(page);
page_cache_release(page);
spin_lock(&pagecache_lock);
}
473 spin_unlock(&pagecache_lock);
}
/*
* Add a page to the inode page cache.
*
* The caller must have locked the page and
* set all the page flags correctly..
*/
482 void add_to_page_cache_locked(struct page * page, struct address_space *mapping, unsigned long index)
{
484 if (!PageLocked(page))
485 BUG();
page_cache_get(page);
spin_lock(&pagecache_lock);
page->index = index;
add_page_to_inode_queue(mapping, page);
add_page_to_hash_queue(page, page_hash(mapping, index));
lru_cache_add(page);
493 spin_unlock(&pagecache_lock);
}
/*
* This adds a page to the page cache, starting out as locked,
* owned by us, but unreferenced, not uptodate and with no errors.
*/
500 static inline void __add_to_page_cache(struct page * page,
struct address_space *mapping, unsigned long offset,
struct page **hash)
{
unsigned long flags;
506 if (PageLocked(page))
507 BUG();
flags = page->flags & ~((1 << PG_uptodate) | (1 << PG_error) | (1 << PG_dirty) | (1 << PG_referenced) | (1 << PG_arch_1));
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);
lru_cache_add(page);
}
518 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));
522 spin_unlock(&pagecache_lock);
}
525 static 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;
536 if (!alias) {
__add_to_page_cache(page,mapping,offset,hash);
err = 0;
}
541 spin_unlock(&pagecache_lock);
542 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.
*/
549 static inline int page_cache_read(struct file * file, unsigned long offset)
{
struct inode *inode = file->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
struct page **hash = page_hash(mapping, offset);
struct page *page;
spin_lock(&pagecache_lock);
page = __find_page_nolock(mapping, offset, *hash);
558 spin_unlock(&pagecache_lock);
559 if (page)
560 return 0;
page = page_cache_alloc();
563 if (!page)
564 return -ENOMEM;
566 if (!add_to_page_cache_unique(page, mapping, offset, hash)) {
int error = mapping->a_ops->readpage(file, page);
page_cache_release(page);
569 return error;
}
/*
* We arrive here in the unlikely event that someone
* raced with us and added our page to the cache first.
*/
page_cache_free(page);
576 return 0;
}
/*
* Read in an entire cluster at once. A cluster is usually a 64k-
* aligned block that includes the page requested in "offset."
*/
583 static int read_cluster_nonblocking(struct file * file, unsigned long offset,
unsigned long filesize)
{
unsigned long pages = CLUSTER_PAGES;
offset = CLUSTER_OFFSET(offset);
589 while ((pages-- > 0) && (offset < filesize)) {
int error = page_cache_read(file, offset);
591 if (error < 0)
592 return error;
offset ++;
}
596 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..
*/
606 void ___wait_on_page(struct page *page)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
add_wait_queue(&page->wait, &wait);
612 do {
sync_page(page);
614 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
615 if (!PageLocked(page))
616 break;
run_task_queue(&tq_disk);
schedule();
619 } while (PageLocked(page));
tsk->state = TASK_RUNNING;
remove_wait_queue(&page->wait, &wait);
}
/*
* Get a lock on the page, assuming we need to sleep
* to get it..
*/
628 static void __lock_page(struct page *page)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
add_wait_queue_exclusive(&page->wait, &wait);
634 for (;;) {
sync_page(page);
636 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
637 if (PageLocked(page)) {
run_task_queue(&tq_disk);
schedule();
640 continue;
}
642 if (!TryLockPage(page))
643 break;
}
tsk->state = TASK_RUNNING;
remove_wait_queue(&page->wait, &wait);
}
/*
* Get an exclusive lock on the page, optimistically
* assuming it's not locked..
*/
654 void lock_page(struct page *page)
{
656 if (TryLockPage(page))
__lock_page(page);
}
/*
* a rather lightweight function, finding and getting a reference to a
* hashed page atomically, waiting for it if it's locked.
*/
664 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);
675 if (page)
page_cache_get(page);
677 spin_unlock(&pagecache_lock);
678 return page;
}
/*
* Get the lock to a page atomically.
*/
684 struct page * __find_lock_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.
*/
repeat:
spin_lock(&pagecache_lock);
page = __find_page_nolock(mapping, offset, *hash);
696 if (page) {
page_cache_get(page);
698 spin_unlock(&pagecache_lock);
lock_page(page);
/* Is the page still hashed? Ok, good.. */
703 if (page->mapping)
704 return page;
/* Nope: we raced. Release and try again.. */
707 UnlockPage(page);
page_cache_release(page);
709 goto repeat;
}
711 spin_unlock(&pagecache_lock);
712 return NULL;
}
#if 0
#define PROFILE_READAHEAD
#define DEBUG_READAHEAD
#endif
/*
* We combine this with read-ahead to deactivate pages when we
* think there's sequential IO going on. Note that this is
* harmless since we don't actually evict the pages from memory
* but just move them to the inactive list.
*
* TODO:
* - make the readahead code smarter
* - move readahead to the VMA level so we can do the same
* trick with mmap()
*
* Rik van Riel, 2000
*/
733 static void drop_behind(struct file * file, unsigned long index)
{
struct inode *inode = file->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
struct page **hash;
struct page *page;
unsigned long start;
/* Nothing to drop-behind if we're on the first page. */
742 if (!index)
743 return;
745 if (index > file->f_rawin)
start = index - file->f_rawin;
747 else
start = 0;
/*
* Go backwards from index-1 and drop all pages in the
* readahead window. Since the readahead window may have
* been increased since the last time we were called, we
* stop when the page isn't there.
*/
spin_lock(&pagecache_lock);
757 while (--index >= start) {
hash = page_hash(mapping, index);
page = __find_page_nolock(mapping, index, *hash);
760 if (!page)
761 break;
deactivate_page(page);
}
764 spin_unlock(&pagecache_lock);
}
/*
* 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).
*/
885 static inline int get_max_readahead(struct inode * inode)
{
887 if (!inode->i_dev || !max_readahead[MAJOR(inode->i_dev)])
888 return MAX_READAHEAD;
889 return max_readahead[MAJOR(inode->i_dev)][MINOR(inode->i_dev)];
}
892 static void generic_file_readahead(int reada_ok,
struct file * filp, struct inode * inode,
struct page * page)
{
unsigned long end_index = inode->i_size >> PAGE_CACHE_SHIFT;
unsigned long index = page->index;
unsigned long max_ahead, ahead;
unsigned long raend;
int max_readahead = get_max_readahead(inode);
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.
*/
913 if (PageLocked(page)) {
914 if (!filp->f_ralen || index >= raend || index + filp->f_rawin < raend) {
raend = index;
916 if (raend < end_index)
max_ahead = filp->f_ramax;
filp->f_rawin = 0;
filp->f_ralen = 1;
920 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 &&
935 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;
943 if (raend < end_index)
max_ahead = filp->f_ramax + 1;
946 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;
958 while (ahead < max_ahead) {
ahead ++;
960 if ((raend + ahead) >= end_index)
961 break;
962 if (page_cache_read(filp, raend + ahead) < 0)
963 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.
*/
976 if (ahead) {
977 if (reada_ok == 2) {
run_task_queue(&tq_disk);
}
filp->f_ralen += ahead;
filp->f_rawin += filp->f_ralen;
filp->f_raend = raend + ahead + 1;
filp->f_ramax += filp->f_ramax;
987 if (filp->f_ramax > max_readahead)
filp->f_ramax = max_readahead;
/*
* Move the pages that have already been passed
* to the inactive list.
*/
drop_behind(filp, index);
#ifdef PROFILE_READAHEAD
profile_readahead((reada_ok == 2), filp);
#endif
}
1001 return;
}
/*
* 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.
*/
1013 void do_generic_file_read(struct file * filp, loff_t *ppos, read_descriptor_t * desc, read_actor_t actor)
{
struct inode *inode = filp->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
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.
*/
1034 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;
1040 } 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.
*/
1050 if (!index && offset + desc->count <= (PAGE_CACHE_SIZE >> 1)) {
filp->f_ramax = 0;
1052 } else {
unsigned long needed;
needed = ((offset + desc->count) >> PAGE_CACHE_SHIFT) + 1;
1057 if (filp->f_ramax < needed)
filp->f_ramax = needed;
1060 if (reada_ok && filp->f_ramax < MIN_READAHEAD)
filp->f_ramax = MIN_READAHEAD;
1062 if (filp->f_ramax > max_readahead)
filp->f_ramax = max_readahead;
}
1066 for (;;) {
struct page *page, **hash;
unsigned long end_index, nr;
end_index = inode->i_size >> PAGE_CACHE_SHIFT;
1071 if (index > end_index)
1072 break;
nr = PAGE_CACHE_SIZE;
1074 if (index == end_index) {
nr = inode->i_size & ~PAGE_CACHE_MASK;
1076 if (nr <= offset)
1077 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);
1089 if (!page)
1090 goto no_cached_page;
found_page:
page_cache_get(page);
1093 spin_unlock(&pagecache_lock);
1095 if (!Page_Uptodate(page))
1096 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.
*/
1103 if (mapping->i_mmap_shared != NULL)
1104 flush_dcache_page(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).
*/
nr = actor(desc, page, offset, nr);
offset += nr;
index += offset >> PAGE_CACHE_SHIFT;
offset &= ~PAGE_CACHE_MASK;
page_cache_release(page);
1122 if (nr && desc->count)
1123 continue;
1124 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);
1132 if (Page_Uptodate(page))
1133 goto page_ok;
/* Get exclusive access to the page ... */
lock_page(page);
/* Did it get unhashed before we got the lock? */
1139 if (!page->mapping) {
1140 UnlockPage(page);
page_cache_release(page);
1142 continue;
}
/* Did somebody else fill it already? */
1146 if (Page_Uptodate(page)) {
1147 UnlockPage(page);
1148 goto page_ok;
}
readpage:
/* ... and start the actual read. The read will unlock the page. */
error = mapping->a_ops->readpage(filp, page);
1155 if (!error) {
1156 if (Page_Uptodate(page))
1157 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);
1162 if (Page_Uptodate(page))
1163 goto page_ok;
error = -EIO;
}
/* UHHUH! A synchronous read error occurred. Report it */
desc->error = error;
page_cache_release(page);
1170 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.
*/
1179 if (!cached_page) {
1180 spin_unlock(&pagecache_lock);
cached_page = page_cache_alloc();
1182 if (!cached_page) {
desc->error = -ENOMEM;
1184 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);
1193 if (page)
1194 goto found_page;
}
/*
* Ok, add the new page to the hash-queues...
*/
page = cached_page;
__add_to_page_cache(page, mapping, index, hash);
1202 spin_unlock(&pagecache_lock);
cached_page = NULL;
1205 goto readpage;
}
*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
filp->f_reada = 1;
1210 if (cached_page)
page_cache_free(cached_page);
UPDATE_ATIME(inode);
}
1215 static 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;
1220 if (size > count)
size = count;
kaddr = kmap(page);
left = __copy_to_user(desc->buf, kaddr + offset, size);
1225 kunmap(page);
1227 if (left) {
size -= left;
desc->error = -EFAULT;
}
desc->count = count - size;
desc->written += size;
desc->buf += size;
1234 return size;
}
/*
* This is the "read()" routine for all filesystems
* that can use the page cache directly.
*/
1241 ssize_t generic_file_read(struct file * filp, char * buf, size_t count, loff_t *ppos)
{
ssize_t retval;
retval = -EFAULT;
1246 if (access_ok(VERIFY_WRITE, buf, count)) {
retval = 0;
1249 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;
1259 if (!retval)
retval = desc.error;
}
}
1263 return retval;
}
1266 static int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset , unsigned long size)
{
char *kaddr;
ssize_t written;
unsigned long count = desc->count;
struct file *file = (struct file *) desc->buf;
mm_segment_t old_fs;
1274 if (size > count)
size = count;
old_fs = get_fs();
set_fs(KERNEL_DS);
kaddr = kmap(page);
written = file->f_op->write(file, kaddr + offset, size, &file->f_pos);
1281 kunmap(page);
set_fs(old_fs);
1283 if (written < 0) {
desc->error = written;
written = 0;
}
desc->count = count - written;
desc->written += written;
1289 return written;
}
1292 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);
1303 if (!in_file)
1304 goto out;
1305 if (!(in_file->f_mode & FMODE_READ))
1306 goto fput_in;
retval = -EINVAL;
in_inode = in_file->f_dentry->d_inode;
1309 if (!in_inode)
1310 goto fput_in;
1311 if (!in_inode->i_mapping->a_ops->readpage)
1312 goto fput_in;
retval = locks_verify_area(FLOCK_VERIFY_READ, in_inode, in_file, in_file->f_pos, count);
1314 if (retval)
1315 goto fput_in;
/*
* Get output file, and verify that it is ok..
*/
retval = -EBADF;
out_file = fget(out_fd);
1322 if (!out_file)
1323 goto fput_in;
1324 if (!(out_file->f_mode & FMODE_WRITE))
1325 goto fput_out;
retval = -EINVAL;
1327 if (!out_file->f_op || !out_file->f_op->write)
1328 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);
1331 if (retval)
1332 goto fput_out;
retval = 0;
1335 if (count) {
read_descriptor_t desc;
loff_t pos = 0, *ppos;
retval = -EFAULT;
ppos = &in_file->f_pos;
1341 if (offset) {
1342 if (get_user(pos, offset))
1343 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;
1354 if (!retval)
retval = desc.error;
1356 if (offset)
put_user(pos, offset);
}
fput_out:
fput(out_file);
fput_in:
fput(in_file);
out:
1365 return retval;
}
/*
* 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.
*/
1373 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. */
1382 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.
*/
1390 if ((pgoff + (ra_window >> 1)) == vma->vm_raend) {
unsigned long start = vma->vm_pgoff + vma->vm_raend;
unsigned long end = start + ra_window;
1394 if (end > ((vma->vm_end >> PAGE_SHIFT) + vma->vm_pgoff))
end = (vma->vm_end >> PAGE_SHIFT) + vma->vm_pgoff;
1396 if (start > end)
1397 return;
1399 while ((start < end) && (start < filesize)) {
if (read_cluster_nonblocking(vma->vm_file,
1401 start, filesize) < 0)
1402 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. */
1409 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;
}
1420 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.
*/
1431 struct page * filemap_nopage(struct vm_area_struct * area,
unsigned long address, int no_share)
{
int error;
struct file *file = area->vm_file;
struct inode *inode = file->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
struct page *page, **hash, *old_page;
unsigned long size, pgoff;
pgoff = ((address - 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;
1449 if ((pgoff >= size) && (area->vm_mm == current->mm))
1450 return NULL;
/*
* Do we have something in the page cache already?
*/
hash = page_hash(mapping, pgoff);
retry_find:
page = __find_get_page(mapping, pgoff, hash);
1458 if (!page)
1459 goto no_cached_page;
/*
* Ok, found a page in the page cache, now we need to check
* that it's up-to-date.
*/
1465 if (!Page_Uptodate(page))
1466 goto page_not_uptodate;
success:
/*
* Try read-ahead for sequential areas.
*/
1472 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..
*/
old_page = page;
1480 if (no_share) {
struct page *new_page = page_cache_alloc();
1483 if (new_page) {
copy_user_highpage(new_page, old_page, address);
1485 flush_page_to_ram(new_page);
1486 } else
new_page = NOPAGE_OOM;
page_cache_release(page);
1489 return new_page;
}
1492 flush_page_to_ram(old_page);
1493 return old_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.
*/
1503 if ((pgoff < size) && !VM_RandomReadHint(area))
error = read_cluster_nonblocking(file, pgoff, size);
1505 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.
*/
1513 if (error >= 0)
1514 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.
*/
1521 if (error == -ENOMEM)
1522 return NOPAGE_OOM;
1523 return NULL;
page_not_uptodate:
lock_page(page);
/* Did it get unhashed while we waited for it? */
1529 if (!page->mapping) {
1530 UnlockPage(page);
page_cache_release(page);
1532 goto retry_all;
}
/* Did somebody else get it up-to-date? */
1536 if (Page_Uptodate(page)) {
1537 UnlockPage(page);
1538 goto success;
}
1541 if (!mapping->a_ops->readpage(file, page)) {
wait_on_page(page);
1543 if (Page_Uptodate(page))
1544 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? */
1556 if (!page->mapping) {
1557 UnlockPage(page);
page_cache_release(page);
1559 goto retry_all;
}
/* Somebody else successfully read it in? */
1563 if (Page_Uptodate(page)) {
1564 UnlockPage(page);
1565 goto success;
}
ClearPageError(page);
1568 if (!mapping->a_ops->readpage(file, page)) {
wait_on_page(page);
1570 if (Page_Uptodate(page))
1571 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);
1579 return NULL;
}
/* Called with mm->page_table_lock held to protect against other
* threads/the swapper from ripping pte's out from under us.
*/
1585 static inline int filemap_sync_pte(pte_t * ptep, struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
{
pte_t pte = *ptep;
1590 if (pte_present(pte) && ptep_test_and_clear_dirty(ptep)) {
struct page *page = pte_page(pte);
flush_tlb_page(vma, address);
set_page_dirty(page);
}
1595 return 0;
}
1598 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;
1606 if (pmd_none(*pmd))
1607 return 0;
1608 if (pmd_bad(*pmd)) {
pmd_ERROR(*pmd);
1610 pmd_clear(pmd);
1611 return 0;
}
pte = pte_offset(pmd, address);
offset += address & PMD_MASK;
address &= ~PMD_MASK;
end = address + size;
1617 if (end > PMD_SIZE)
end = PMD_SIZE;
error = 0;
1620 do {
error |= filemap_sync_pte(pte, vma, address + offset, flags);
address += PAGE_SIZE;
pte++;
1624 } while (address && (address < end));
1625 return error;
}
1628 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;
1636 if (pgd_none(*pgd))
1637 return 0;
1638 if (pgd_bad(*pgd)) {
pgd_ERROR(*pgd);
1640 pgd_clear(pgd);
1641 return 0;
}
pmd = pmd_offset(pgd, address);
offset = address & PGDIR_MASK;
address &= ~PGDIR_MASK;
end = address + size;
1647 if (end > PGDIR_SIZE)
end = PGDIR_SIZE;
error = 0;
1650 do {
error |= filemap_sync_pte_range(pmd, address, end - address, vma, offset, flags);
address = (address + PMD_SIZE) & PMD_MASK;
pmd++;
1654 } while (address && (address < end));
1655 return error;
}
1658 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);
1671 flush_cache_range(vma->vm_mm, end - size, end);
1672 if (address >= end)
1673 BUG();
1674 do {
error |= filemap_sync_pmd_range(dir, address, end - address, vma, flags);
address = (address + PGDIR_SIZE) & PGDIR_MASK;
dir++;
1678 } while (address && (address < end));
flush_tlb_range(vma->vm_mm, end - size, end);
1681 spin_unlock(&vma->vm_mm->page_table_lock);
1683 return error;
}
/*
* Shared mappings need to be able to do the right thing at
* close/unmap/sync. They will also use the private file as
* backing-store for swapping..
*/
static struct vm_operations_struct file_shared_mmap = {
nopage: filemap_nopage,
};
/*
* Private mappings just need to be able to load in the map.
*
* (This is actually used for shared mappings as well, if we
* know they can't ever get write permissions..)
*/
static struct vm_operations_struct file_private_mmap = {
nopage: filemap_nopage,
};
/* This is used for a general mmap of a disk file */
1707 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
{
struct vm_operations_struct * ops;
struct inode *inode = file->f_dentry->d_inode;
ops = &file_private_mmap;
1713 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) {
1714 if (!inode->i_mapping->a_ops->writepage)
1715 return -EINVAL;
ops = &file_shared_mmap;
}
1718 if (!inode->i_sb || !S_ISREG(inode->i_mode))
1719 return -EACCES;
1720 if (!inode->i_mapping->a_ops->readpage)
1721 return -ENOEXEC;
UPDATE_ATIME(inode);
vma->vm_ops = ops;
1724 return 0;
}
/*
* The msync() system call.
*/
1731 static int msync_interval(struct vm_area_struct * vma,
unsigned long start, unsigned long end, int flags)
{
struct file * file = vma->vm_file;
1735 if (file && (vma->vm_flags & VM_SHARED)) {
int error;
error = filemap_sync(vma, start, end-start, flags);
1739 if (!error && (flags & MS_SYNC)) {
struct inode * inode = file->f_dentry->d_inode;
down(&inode->i_sem);
filemap_fdatasync(inode->i_mapping);
1743 if (file->f_op && file->f_op->fsync)
error = file->f_op->fsync(file, file->f_dentry, 1);
filemap_fdatawait(inode->i_mapping);
up(&inode->i_sem);
}
1748 return error;
}
1750 return 0;
}
1753 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(¤t->mm->mmap_sem);
1760 if (start & ~PAGE_MASK)
1761 goto out;
len = (len + ~PAGE_MASK) & PAGE_MASK;
end = start + len;
1764 if (end < start)
1765 goto out;
1766 if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
1767 goto out;
error = 0;
1769 if (end == start)
1770 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;
1777 for (;;) {
/* Still start < end. */
error = -EFAULT;
1780 if (!vma)
1781 goto out;
/* Here start < vma->vm_end. */
1783 if (start < vma->vm_start) {
unmapped_error = -EFAULT;
start = vma->vm_start;
}
/* Here vma->vm_start <= start < vma->vm_end. */
1788 if (end <= vma->vm_end) {
1789 if (start < end) {
error = msync_interval(vma, start, end, flags);
1791 if (error)
1792 goto out;
}
error = unmapped_error;
1795 goto out;
}
/* Here vma->vm_start <= start < vma->vm_end < end. */
error = msync_interval(vma, start, vma->vm_end, flags);
1799 if (error)
1800 goto out;
start = vma->vm_end;
vma = vma->vm_next;
}
out:
up(¤t->mm->mmap_sem);
1806 return error;
}
1809 static inline void setup_read_behavior(struct vm_area_struct * vma,
int behavior)
{
VM_ClearReadHint(vma);
1813 switch(behavior) {
1814 case MADV_SEQUENTIAL:
vma->vm_flags |= VM_SEQ_READ;
1816 break;
1817 case MADV_RANDOM:
vma->vm_flags |= VM_RAND_READ;
1819 break;
1820 default:
1821 break;
}
1823 return;
}
1826 static long madvise_fixup_start(struct vm_area_struct * vma,
unsigned long end, int behavior)
{
struct vm_area_struct * n;
n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1832 if (!n)
1833 return -EAGAIN;
*n = *vma;
n->vm_end = end;
setup_read_behavior(n, behavior);
n->vm_raend = 0;
get_file(n->vm_file);
1839 if (n->vm_ops && n->vm_ops->open)
n->vm_ops->open(n);
lock_vma_mappings(vma);
spin_lock(&vma->vm_mm->page_table_lock);
vma->vm_pgoff += (end - vma->vm_start) >> PAGE_SHIFT;
vma->vm_start = end;
__insert_vm_struct(current->mm, n);
1846 spin_unlock(&vma->vm_mm->page_table_lock);
unlock_vma_mappings(vma);
1848 return 0;
}
1851 static long madvise_fixup_end(struct vm_area_struct * vma,
unsigned long start, int behavior)
{
struct vm_area_struct * n;
n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1857 if (!n)
1858 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;
get_file(n->vm_file);
1865 if (n->vm_ops && n->vm_ops->open)
n->vm_ops->open(n);
lock_vma_mappings(vma);
spin_lock(&vma->vm_mm->page_table_lock);
vma->vm_end = start;
__insert_vm_struct(current->mm, n);
1871 spin_unlock(&vma->vm_mm->page_table_lock);
unlock_vma_mappings(vma);
1873 return 0;
}
1876 static long madvise_fixup_middle(struct vm_area_struct * vma,
unsigned long start, unsigned long end, int behavior)
{
struct vm_area_struct * left, * right;
left = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1882 if (!left)
1883 return -EAGAIN;
right = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1885 if (!right) {
kmem_cache_free(vm_area_cachep, left);
1887 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;
atomic_add(2, &vma->vm_file->f_count);
1898 if (vma->vm_ops && vma->vm_ops->open) {
vma->vm_ops->open(left);
vma->vm_ops->open(right);
}
lock_vma_mappings(vma);
spin_lock(&vma->vm_mm->page_table_lock);
vma->vm_pgoff += (start - vma->vm_start) >> PAGE_SHIFT;
vma->vm_start = start;
vma->vm_end = end;
setup_read_behavior(vma, behavior);
vma->vm_raend = 0;
__insert_vm_struct(current->mm, left);
__insert_vm_struct(current->mm, right);
1911 spin_unlock(&vma->vm_mm->page_table_lock);
unlock_vma_mappings(vma);
1913 return 0;
}
/*
* We can potentially split a vm area into separate
* areas, each area with its own behavior.
*/
1920 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 */
1926 if (vma->vm_mm->map_count > MAX_MAP_COUNT)
1927 return -ENOMEM;
1929 if (start == vma->vm_start) {
1930 if (end == vma->vm_end) {
setup_read_behavior(vma, behavior);
vma->vm_raend = 0;
1933 } else
error = madvise_fixup_start(vma, end, behavior);
1935 } else {
1936 if (end == vma->vm_end)
error = madvise_fixup_end(vma, start, behavior);
1938 else
error = madvise_fixup_middle(vma, start, end, behavior);
}
1942 return error;
}
/*
* Schedule all required I/O operations, then run the disk queue
* to make sure they are started. Do not wait for completion.
*/
1949 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. */
1957 if (!vma->vm_file)
1958 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;
1964 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 */
1972 if ((vma->vm_mm->rss + (end - start)) > rlim_rss)
1973 return error;
/* round to cluster boundaries if this isn't a "random" area. */
1976 if (!VM_RandomReadHint(vma)) {
start = CLUSTER_OFFSET(start);
end = CLUSTER_OFFSET(end + CLUSTER_PAGES - 1);
1980 while ((start < end) && (start < size)) {
error = read_cluster_nonblocking(file, start, size);
start += CLUSTER_PAGES;
1983 if (error < 0)
1984 break;
}
1986 } else {
1987 while ((start < end) && (start < size)) {
error = page_cache_read(file, start);
start++;
1990 if (error < 0)
1991 break;
}
}
/* Don't wait for someone else to push these requests. */
run_task_queue(&tq_disk);
1998 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).
*/
2020 static long madvise_dontneed(struct vm_area_struct * vma,
unsigned long start, unsigned long end)
{
2023 if (vma->vm_flags & VM_LOCKED)
2024 return -EINVAL;
2026 flush_cache_range(vma->vm_mm, start, end);
zap_page_range(vma->vm_mm, start, end - start);
flush_tlb_range(vma->vm_mm, start, end);
2029 return 0;
}
2032 static long madvise_vma(struct vm_area_struct * vma, unsigned long start,
unsigned long end, int behavior)
{
long error = -EBADF;
2037 switch (behavior) {
2038 case MADV_NORMAL:
2039 case MADV_SEQUENTIAL:
2040 case MADV_RANDOM:
error = madvise_behavior(vma, start, end, behavior);
2042 break;
2044 case MADV_WILLNEED:
error = madvise_willneed(vma, start, end);
2046 break;
2048 case MADV_DONTNEED:
error = madvise_dontneed(vma, start, end);
2050 break;
2052 default:
error = -EINVAL;
2054 break;
}
2057 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.
*/
2094 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(¤t->mm->mmap_sem);
2103 if (start & ~PAGE_MASK)
2104 goto out;
len = (len + ~PAGE_MASK) & PAGE_MASK;
end = start + len;
2107 if (end < start)
2108 goto out;
error = 0;
2111 if (end == start)
2112 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);
2119 for (;;) {
/* Still start < end. */
error = -ENOMEM;
2122 if (!vma)
2123 goto out;
/* Here start < vma->vm_end. */
2126 if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
}
/* Here vma->vm_start <= start < vma->vm_end. */
2132 if (end <= vma->vm_end) {
2133 if (start < end) {
error = madvise_vma(vma, start, end,
behavior);
2136 if (error)
2137 goto out;
}
error = unmapped_error;
2140 goto out;
}
/* Here vma->vm_start <= start < vma->vm_end < end. */
error = madvise_vma(vma, start, vma->vm_end, behavior);
2145 if (error)
2146 goto out;
start = vma->vm_end;
vma = vma->vm_next;
}
out:
up(¤t->mm->mmap_sem);
2153 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.
*/
2162 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_data;
struct page * page, ** hash = page_hash(as, pgoff);
spin_lock(&pagecache_lock);
page = __find_page_nolock(as, pgoff, *hash);
2171 if ((page) && (Page_Uptodate(page)))
present = 1;
2173 spin_unlock(&pagecache_lock);
2175 return present;
}
2178 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;
2185 if (!vma->vm_file)
2186 return error;
start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2189 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);
2195 if (!tmp)
2196 return error;
/* (end - start) is # of pages, and also # of bytes in "vec */
remaining = (end - start),
error = 0;
2202 for (i = 0; remaining > 0; remaining -= PAGE_SIZE, i++) {
int j = 0;
long thispiece = (remaining < PAGE_SIZE) ?
remaining : PAGE_SIZE;
2207 while (j < thispiece)
tmp[j++] = mincore_page(vma, start++);
2210 if (copy_to_user(vec + PAGE_SIZE * i, tmp, thispiece)) {
error = -EFAULT;
2212 break;
}
}
free_page((unsigned long) tmp);
2217 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.
*/
2245 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(¤t->mm->mmap_sem);
2256 if (start & ~PAGE_CACHE_MASK)
2257 goto out;
len = (len + ~PAGE_CACHE_MASK) & PAGE_CACHE_MASK;
end = start + len;
2260 if (end < start)
2261 goto out;
error = 0;
2264 if (end == start)
2265 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);
2272 for (;;) {
/* Still start < end. */
error = -ENOMEM;
2275 if (!vma)
2276 goto out;
/* Here start < vma->vm_end. */
2279 if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
}
/* Here vma->vm_start <= start < vma->vm_end. */
2285 if (end <= vma->vm_end) {
2286 if (start < end) {
error = mincore_vma(vma, start, end,
&vec[index]);
2289 if (error)
2290 goto out;
}
error = unmapped_error;
2293 goto out;
}
/* Here vma->vm_start <= start < vma->vm_end < end. */
error = mincore_vma(vma, start, vma->vm_end, &vec[index]);
2298 if (error)
2299 goto out;
index += (vma->vm_end - start) >> PAGE_CACHE_SHIFT;
start = vma->vm_end;
vma = vma->vm_next;
}
out:
up(¤t->mm->mmap_sem);
2307 return error;
}
static inline
2311 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);
2321 if (!page) {
2322 if (!cached_page) {
cached_page = page_cache_alloc();
2324 if (!cached_page)
2325 return ERR_PTR(-ENOMEM);
}
page = cached_page;
2328 if (add_to_page_cache_unique(page, mapping, index, hash))
2329 goto repeat;
cached_page = NULL;
err = filler(data, page);
2332 if (err < 0) {
page_cache_release(page);
page = ERR_PTR(err);
}
}
2337 if (cached_page)
page_cache_free(cached_page);
2339 return page;
}
/*
* Read into the page cache. If a page already exists,
* and Page_Uptodate() is not set, try to fill the page.
*/
2346 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);
2356 if (IS_ERR(page) || Page_Uptodate(page))
2357 goto out;
lock_page(page);
2360 if (!page->mapping) {
2361 UnlockPage(page);
page_cache_release(page);
2363 goto retry;
}
2365 if (Page_Uptodate(page)) {
2366 UnlockPage(page);
2367 goto out;
}
err = filler(data, page);
2370 if (err < 0) {
page_cache_release(page);
page = ERR_PTR(err);
}
out:
2375 return page;
}
2378 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);
2384 if (!page) {
2385 if (!*cached_page) {
*cached_page = page_cache_alloc();
2387 if (!*cached_page)
2388 return NULL;
}
page = *cached_page;
2391 if (add_to_page_cache_unique(page, mapping, index, hash))
2392 goto repeat;
*cached_page = NULL;
}
2395 return page;
}
/*
* Returns locked page at given index in given cache, creating it if needed.
*/
2402 struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
{
struct page *cached_page = NULL;
struct page *page = __grab_cache_page(mapping,index,&cached_page);
2406 if (cached_page)
page_cache_free(cached_page);
2408 return page;
}
2411 static 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;
2420 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
2442 generic_file_write(struct file *file,const char *buf,size_t count,loff_t *ppos)
{
struct inode *inode = file->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
unsigned long limit = current->rlim[RLIMIT_FSIZE].rlim_cur;
loff_t pos;
struct page *page, *cached_page;
unsigned long written;
long status;
int err;
cached_page = NULL;
down(&inode->i_sem);
pos = *ppos;
err = -EINVAL;
2459 if (pos < 0)
2460 goto out;
err = file->f_error;
2463 if (err) {
file->f_error = 0;
2465 goto out;
}
written = 0;
2470 if (file->f_flags & O_APPEND)
pos = inode->i_size;
/*
* Check whether we've reached the file size limit.
*/
err = -EFBIG;
2477 if (limit != RLIM_INFINITY) {
2478 if (pos >= limit) {
send_sig(SIGXFSZ, current, 0);
2480 goto out;
}
2482 if (count > limit - pos) {
send_sig(SIGXFSZ, current, 0);
count = limit - pos;
}
}
status = 0;
2489 if (count) {
remove_suid(inode);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
mark_inode_dirty_sync(inode);
}
2495 while (count) {
unsigned long bytes, index, offset;
char *kaddr;
int deactivate = 1;
/*
* 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;
2507 if (bytes > count) {
bytes = count;
deactivate = 0;
}
/*
* 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);
2525 if (!page)
2526 break;
/* We have exclusive IO access to the page.. */
2529 if (!PageLocked(page)) {
2530 PAGE_BUG(page);
}
status = mapping->a_ops->prepare_write(file, page, offset, offset+bytes);
2534 if (status)
2535 goto unlock;
kaddr = page_address(page);
status = copy_from_user(kaddr+offset, buf, bytes);
2538 flush_dcache_page(page);
2539 if (status)
2540 goto fail_write;
status = mapping->a_ops->commit_write(file, page, offset, offset+bytes);
2542 if (!status)
status = bytes;
2545 if (status >= 0) {
written += status;
count -= status;
pos += status;
buf += status;
}
unlock:
/* Mark it unlocked again and drop the page.. */
2553 UnlockPage(page);
2554 if (deactivate)
deactivate_page(page);
page_cache_release(page);
2558 if (status < 0)
2559 break;
}
*ppos = pos;
2563 if (cached_page)
page_cache_free(cached_page);
/* For now, when the user asks for O_SYNC, we'll actually
* provide O_DSYNC. */
2568 if ((status >= 0) && (file->f_flags & O_SYNC))
status = generic_osync_inode(inode, 1); /* 1 means datasync */
err = written ? written : status;
out:
up(&inode->i_sem);
2575 return err;
fail_write:
status = -EFAULT;
ClearPageUptodate(page);
2579 kunmap(page);
2580 goto unlock;
}
2583 void __init page_cache_init(unsigned long mempages)
{
unsigned long htable_size, order;
htable_size = mempages;
htable_size *= sizeof(struct page *);
2589 for(order = 0; (PAGE_SIZE << order) < htable_size; order++)
;
2592 do {
unsigned long tmp = (PAGE_SIZE << order) / sizeof(struct page *);
page_hash_bits = 0;
2596 while((tmp >>= 1UL) != 0UL)
page_hash_bits++;
page_hash_table = (struct page **)
__get_free_pages(GFP_ATOMIC, order);
2601 } 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));
2605 if (!page_hash_table)
panic("Failed to allocate page hash table\n");
memset((void *)page_hash_table, 0, PAGE_HASH_SIZE * sizeof(struct page *));
}