linux/mm/truncate.c

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/*
* mm/truncate.c - code for taking down pages from address_spaces
*
* Copyright (C) 2002, Linus Torvalds
*
* 10Sep2002 akpm@zip.com.au
* Initial version.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/pagevec.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/buffer_head.h> /* grr. try_to_release_page,
do_invalidatepage */
/**
* do_invalidatepage - invalidate part of all of a page
* @page: the page which is affected
* @offset: the index of the truncation point
*
* do_invalidatepage() is called when all or part of the page has become
* invalidated by a truncate operation.
*
* do_invalidatepage() does not have to release all buffers, but it must
* ensure that no dirty buffer is left outside @offset and that no I/O
* is underway against any of the blocks which are outside the truncation
* point. Because the caller is about to free (and possibly reuse) those
* blocks on-disk.
*/
void do_invalidatepage(struct page *page, unsigned long offset)
{
void (*invalidatepage)(struct page *, unsigned long);
invalidatepage = page->mapping->a_ops->invalidatepage;
[PATCH] BLOCK: Make it possible to disable the block layer [try #6] Make it possible to disable the block layer. Not all embedded devices require it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require the block layer to be present. This patch does the following: (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev support. (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls an item that uses the block layer. This includes: (*) Block I/O tracing. (*) Disk partition code. (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS. (*) The SCSI layer. As far as I can tell, even SCSI chardevs use the block layer to do scheduling. Some drivers that use SCSI facilities - such as USB storage - end up disabled indirectly from this. (*) Various block-based device drivers, such as IDE and the old CDROM drivers. (*) MTD blockdev handling and FTL. (*) JFFS - which uses set_bdev_super(), something it could avoid doing by taking a leaf out of JFFS2's book. (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is, however, still used in places, and so is still available. (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and parts of linux/fs.h. (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK. (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK. (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK is not enabled. (*) fs/no-block.c is created to hold out-of-line stubs and things that are required when CONFIG_BLOCK is not set: (*) Default blockdev file operations (to give error ENODEV on opening). (*) Makes some /proc changes: (*) /proc/devices does not list any blockdevs. (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK. (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK. (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if given command other than Q_SYNC or if a special device is specified. (*) In init/do_mounts.c, no reference is made to the blockdev routines if CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2. (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return error ENOSYS by way of cond_syscall if so). (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if CONFIG_BLOCK is not set, since they can't then happen. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 18:45:40 +00:00
#ifdef CONFIG_BLOCK
if (!invalidatepage)
invalidatepage = block_invalidatepage;
[PATCH] BLOCK: Make it possible to disable the block layer [try #6] Make it possible to disable the block layer. Not all embedded devices require it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require the block layer to be present. This patch does the following: (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev support. (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls an item that uses the block layer. This includes: (*) Block I/O tracing. (*) Disk partition code. (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS. (*) The SCSI layer. As far as I can tell, even SCSI chardevs use the block layer to do scheduling. Some drivers that use SCSI facilities - such as USB storage - end up disabled indirectly from this. (*) Various block-based device drivers, such as IDE and the old CDROM drivers. (*) MTD blockdev handling and FTL. (*) JFFS - which uses set_bdev_super(), something it could avoid doing by taking a leaf out of JFFS2's book. (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is, however, still used in places, and so is still available. (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and parts of linux/fs.h. (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK. (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK. (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK is not enabled. (*) fs/no-block.c is created to hold out-of-line stubs and things that are required when CONFIG_BLOCK is not set: (*) Default blockdev file operations (to give error ENODEV on opening). (*) Makes some /proc changes: (*) /proc/devices does not list any blockdevs. (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK. (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK. (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if given command other than Q_SYNC or if a special device is specified. (*) In init/do_mounts.c, no reference is made to the blockdev routines if CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2. (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return error ENOSYS by way of cond_syscall if so). (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if CONFIG_BLOCK is not set, since they can't then happen. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 18:45:40 +00:00
#endif
if (invalidatepage)
(*invalidatepage)(page, offset);
}
static inline void truncate_partial_page(struct page *page, unsigned partial)
{
zero_user_page(page, partial, PAGE_CACHE_SIZE - partial, KM_USER0);
if (PagePrivate(page))
do_invalidatepage(page, partial);
}
/*
* This cancels just the dirty bit on the kernel page itself, it
* does NOT actually remove dirty bits on any mmap's that may be
* around. It also leaves the page tagged dirty, so any sync
* activity will still find it on the dirty lists, and in particular,
* clear_page_dirty_for_io() will still look at the dirty bits in
* the VM.
*
* Doing this should *normally* only ever be done when a page
* is truncated, and is not actually mapped anywhere at all. However,
* fs/buffer.c does this when it notices that somebody has cleaned
* out all the buffers on a page without actually doing it through
* the VM. Can you say "ext3 is horribly ugly"? Tought you could.
*/
VM: Remove "clear_page_dirty()" and "test_clear_page_dirty()" functions They were horribly easy to mis-use because of their tempting naming, and they also did way more than any users of them generally wanted them to do. A dirty page can become clean under two circumstances: (a) when we write it out. We have "clear_page_dirty_for_io()" for this, and that function remains unchanged. In the "for IO" case it is not sufficient to just clear the dirty bit, you also have to mark the page as being under writeback etc. (b) when we actually remove a page due to it becoming inaccessible to users, notably because it was truncate()'d away or the file (or metadata) no longer exists, and we thus want to cancel any outstanding dirty state. For the (b) case, we now introduce "cancel_dirty_page()", which only touches the page state itself, and verifies that the page is not mapped (since cancelling writes on a mapped page would be actively wrong as it is still accessible to users). Some filesystems need to be fixed up for this: CIFS, FUSE, JFS, ReiserFS, XFS all use the old confusing functions, and will be fixed separately in subsequent commits (with some of them just removing the offending logic, and others using clear_page_dirty_for_io()). This was confirmed by Martin Michlmayr to fix the apt database corruption on ARM. Cc: Martin Michlmayr <tbm@cyrius.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Andrei Popa <andrei.popa@i-neo.ro> Cc: Andrew Morton <akpm@osdl.org> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: Gordon Farquharson <gordonfarquharson@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-20 21:46:42 +00:00
void cancel_dirty_page(struct page *page, unsigned int account_size)
{
if (TestClearPageDirty(page)) {
struct address_space *mapping = page->mapping;
if (mapping && mapping_cap_account_dirty(mapping)) {
dec_zone_page_state(page, NR_FILE_DIRTY);
if (account_size)
task_io_account_cancelled_write(account_size);
}
}
VM: Remove "clear_page_dirty()" and "test_clear_page_dirty()" functions They were horribly easy to mis-use because of their tempting naming, and they also did way more than any users of them generally wanted them to do. A dirty page can become clean under two circumstances: (a) when we write it out. We have "clear_page_dirty_for_io()" for this, and that function remains unchanged. In the "for IO" case it is not sufficient to just clear the dirty bit, you also have to mark the page as being under writeback etc. (b) when we actually remove a page due to it becoming inaccessible to users, notably because it was truncate()'d away or the file (or metadata) no longer exists, and we thus want to cancel any outstanding dirty state. For the (b) case, we now introduce "cancel_dirty_page()", which only touches the page state itself, and verifies that the page is not mapped (since cancelling writes on a mapped page would be actively wrong as it is still accessible to users). Some filesystems need to be fixed up for this: CIFS, FUSE, JFS, ReiserFS, XFS all use the old confusing functions, and will be fixed separately in subsequent commits (with some of them just removing the offending logic, and others using clear_page_dirty_for_io()). This was confirmed by Martin Michlmayr to fix the apt database corruption on ARM. Cc: Martin Michlmayr <tbm@cyrius.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Andrei Popa <andrei.popa@i-neo.ro> Cc: Andrew Morton <akpm@osdl.org> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: Gordon Farquharson <gordonfarquharson@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-20 21:46:42 +00:00
}
EXPORT_SYMBOL(cancel_dirty_page);
VM: Remove "clear_page_dirty()" and "test_clear_page_dirty()" functions They were horribly easy to mis-use because of their tempting naming, and they also did way more than any users of them generally wanted them to do. A dirty page can become clean under two circumstances: (a) when we write it out. We have "clear_page_dirty_for_io()" for this, and that function remains unchanged. In the "for IO" case it is not sufficient to just clear the dirty bit, you also have to mark the page as being under writeback etc. (b) when we actually remove a page due to it becoming inaccessible to users, notably because it was truncate()'d away or the file (or metadata) no longer exists, and we thus want to cancel any outstanding dirty state. For the (b) case, we now introduce "cancel_dirty_page()", which only touches the page state itself, and verifies that the page is not mapped (since cancelling writes on a mapped page would be actively wrong as it is still accessible to users). Some filesystems need to be fixed up for this: CIFS, FUSE, JFS, ReiserFS, XFS all use the old confusing functions, and will be fixed separately in subsequent commits (with some of them just removing the offending logic, and others using clear_page_dirty_for_io()). This was confirmed by Martin Michlmayr to fix the apt database corruption on ARM. Cc: Martin Michlmayr <tbm@cyrius.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Andrei Popa <andrei.popa@i-neo.ro> Cc: Andrew Morton <akpm@osdl.org> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: Gordon Farquharson <gordonfarquharson@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-20 21:46:42 +00:00
/*
* If truncate cannot remove the fs-private metadata from the page, the page
* becomes anonymous. It will be left on the LRU and may even be mapped into
* user pagetables if we're racing with filemap_nopage().
*
* We need to bale out if page->mapping is no longer equal to the original
* mapping. This happens a) when the VM reclaimed the page while we waited on
* its lock, b) when a concurrent invalidate_mapping_pages got there first and
* c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
*/
static void
truncate_complete_page(struct address_space *mapping, struct page *page)
{
if (page->mapping != mapping)
return;
cancel_dirty_page(page, PAGE_CACHE_SIZE);
if (PagePrivate(page))
do_invalidatepage(page, 0);
ClearPageUptodate(page);
ClearPageMappedToDisk(page);
remove_from_page_cache(page);
page_cache_release(page); /* pagecache ref */
}
/*
* This is for invalidate_mapping_pages(). That function can be called at
* any time, and is not supposed to throw away dirty pages. But pages can
* be marked dirty at any time too, so use remove_mapping which safely
* discards clean, unused pages.
*
* Returns non-zero if the page was successfully invalidated.
*/
static int
invalidate_complete_page(struct address_space *mapping, struct page *page)
{
int ret;
if (page->mapping != mapping)
return 0;
if (PagePrivate(page) && !try_to_release_page(page, 0))
return 0;
ret = remove_mapping(mapping, page);
return ret;
}
/**
* truncate_inode_pages - truncate range of pages specified by start and
* end byte offsets
* @mapping: mapping to truncate
* @lstart: offset from which to truncate
* @lend: offset to which to truncate
*
* Truncate the page cache, removing the pages that are between
* specified offsets (and zeroing out partial page
* (if lstart is not page aligned)).
*
* Truncate takes two passes - the first pass is nonblocking. It will not
* block on page locks and it will not block on writeback. The second pass
* will wait. This is to prevent as much IO as possible in the affected region.
* The first pass will remove most pages, so the search cost of the second pass
* is low.
*
* When looking at page->index outside the page lock we need to be careful to
* copy it into a local to avoid races (it could change at any time).
*
* We pass down the cache-hot hint to the page freeing code. Even if the
* mapping is large, it is probably the case that the final pages are the most
* recently touched, and freeing happens in ascending file offset order.
*/
void truncate_inode_pages_range(struct address_space *mapping,
loff_t lstart, loff_t lend)
{
const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
pgoff_t end;
const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
struct pagevec pvec;
pgoff_t next;
int i;
if (mapping->nrpages == 0)
return;
BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
end = (lend >> PAGE_CACHE_SHIFT);
pagevec_init(&pvec, 0);
next = start;
while (next <= end &&
pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
pgoff_t page_index = page->index;
if (page_index > end) {
next = page_index;
break;
}
if (page_index > next)
next = page_index;
next++;
if (TestSetPageLocked(page))
continue;
if (PageWriteback(page)) {
unlock_page(page);
continue;
}
truncate_complete_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
cond_resched();
}
if (partial) {
struct page *page = find_lock_page(mapping, start - 1);
if (page) {
wait_on_page_writeback(page);
truncate_partial_page(page, partial);
unlock_page(page);
page_cache_release(page);
}
}
next = start;
for ( ; ; ) {
cond_resched();
if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
if (next == start)
break;
next = start;
continue;
}
if (pvec.pages[0]->index > end) {
pagevec_release(&pvec);
break;
}
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
if (page->index > end)
break;
lock_page(page);
wait_on_page_writeback(page);
if (page->index > next)
next = page->index;
next++;
truncate_complete_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
}
}
EXPORT_SYMBOL(truncate_inode_pages_range);
/**
* truncate_inode_pages - truncate *all* the pages from an offset
* @mapping: mapping to truncate
* @lstart: offset from which to truncate
*
* Called under (and serialised by) inode->i_mutex.
*/
void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
{
truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
}
EXPORT_SYMBOL(truncate_inode_pages);
/**
* invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
* @mapping: the address_space which holds the pages to invalidate
* @start: the offset 'from' which to invalidate
* @end: the offset 'to' which to invalidate (inclusive)
*
* This function only removes the unlocked pages, if you want to
* remove all the pages of one inode, you must call truncate_inode_pages.
*
* invalidate_mapping_pages() will not block on IO activity. It will not
* invalidate pages which are dirty, locked, under writeback or mapped into
* pagetables.
*/
unsigned long invalidate_mapping_pages(struct address_space *mapping,
pgoff_t start, pgoff_t end)
{
struct pagevec pvec;
pgoff_t next = start;
unsigned long ret = 0;
int i;
pagevec_init(&pvec, 0);
while (next <= end &&
pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
pgoff_t index;
int lock_failed;
lock_failed = TestSetPageLocked(page);
/*
* We really shouldn't be looking at the ->index of an
* unlocked page. But we're not allowed to lock these
* pages. So we rely upon nobody altering the ->index
* of this (pinned-by-us) page.
*/
index = page->index;
if (index > next)
next = index;
next++;
if (lock_failed)
continue;
if (PageDirty(page) || PageWriteback(page))
goto unlock;
if (page_mapped(page))
goto unlock;
ret += invalidate_complete_page(mapping, page);
unlock:
unlock_page(page);
if (next > end)
break;
}
pagevec_release(&pvec);
}
return ret;
}
EXPORT_SYMBOL(invalidate_mapping_pages);
/*
* This is like invalidate_complete_page(), except it ignores the page's
* refcount. We do this because invalidate_inode_pages2() needs stronger
* invalidation guarantees, and cannot afford to leave pages behind because
* shrink_list() has a temp ref on them, or because they're transiently sitting
* in the lru_cache_add() pagevecs.
*/
static int
invalidate_complete_page2(struct address_space *mapping, struct page *page)
{
if (page->mapping != mapping)
return 0;
if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
return 0;
write_lock_irq(&mapping->tree_lock);
if (PageDirty(page))
goto failed;
BUG_ON(PagePrivate(page));
__remove_from_page_cache(page);
write_unlock_irq(&mapping->tree_lock);
ClearPageUptodate(page);
page_cache_release(page); /* pagecache ref */
return 1;
failed:
write_unlock_irq(&mapping->tree_lock);
return 0;
}
static int do_launder_page(struct address_space *mapping, struct page *page)
{
if (!PageDirty(page))
return 0;
if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
return 0;
return mapping->a_ops->launder_page(page);
}
/**
* invalidate_inode_pages2_range - remove range of pages from an address_space
* @mapping: the address_space
* @start: the page offset 'from' which to invalidate
* @end: the page offset 'to' which to invalidate (inclusive)
*
* Any pages which are found to be mapped into pagetables are unmapped prior to
* invalidation.
*
* Returns -EIO if any pages could not be invalidated.
*/
int invalidate_inode_pages2_range(struct address_space *mapping,
pgoff_t start, pgoff_t end)
{
struct pagevec pvec;
pgoff_t next;
int i;
int ret = 0;
int did_range_unmap = 0;
int wrapped = 0;
pagevec_init(&pvec, 0);
next = start;
while (next <= end && !wrapped &&
pagevec_lookup(&pvec, mapping, next,
min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
pgoff_t page_index;
lock_page(page);
if (page->mapping != mapping) {
unlock_page(page);
continue;
}
page_index = page->index;
next = page_index + 1;
if (next == 0)
wrapped = 1;
if (page_index > end) {
unlock_page(page);
break;
}
wait_on_page_writeback(page);
while (page_mapped(page)) {
if (!did_range_unmap) {
/*
* Zap the rest of the file in one hit.
*/
unmap_mapping_range(mapping,
(loff_t)page_index<<PAGE_CACHE_SHIFT,
(loff_t)(end - page_index + 1)
<< PAGE_CACHE_SHIFT,
0);
did_range_unmap = 1;
} else {
/*
* Just zap this page
*/
unmap_mapping_range(mapping,
(loff_t)page_index<<PAGE_CACHE_SHIFT,
PAGE_CACHE_SIZE, 0);
}
}
ret = do_launder_page(mapping, page);
if (ret == 0 && !invalidate_complete_page2(mapping, page))
ret = -EIO;
unlock_page(page);
}
pagevec_release(&pvec);
cond_resched();
}
return ret;
}
EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
/**
* invalidate_inode_pages2 - remove all pages from an address_space
* @mapping: the address_space
*
* Any pages which are found to be mapped into pagetables are unmapped prior to
* invalidation.
*
* Returns -EIO if any pages could not be invalidated.
*/
int invalidate_inode_pages2(struct address_space *mapping)
{
return invalidate_inode_pages2_range(mapping, 0, -1);
}
EXPORT_SYMBOL_GPL(invalidate_inode_pages2);