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xfs: simplify xfs_vm_writepage

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The writepage implementation in XFS still tries to deal with dirty but
unmapped buffers which used to caused by writes through shared mmaps.  Since
the introduction of ->page_mkwrite these can't happen anymore, so remove the
code dealing with them.

Note that the all_bh variable which causes us to start I/O on all buffers on
the pages was controlled by the count of unmapped buffers, which also
included those not actually dirty.  It's now unconditionally initialized to
0 but set to 1 for the case of small file size extensions.  It probably can
be removed entirely, but that's left for another patch.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
This commit is contained in:
Christoph Hellwig 2010-06-24 09:46:01 +10:00 committed by Alex Elder
parent 89f3b36396
commit 20cb52ebd1
3 changed files with 49 additions and 102 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

139
fs/xfs/linux-2.6/xfs_aops.c
View file

@ -85,18 +85,15 @@ void
xfs_count_page_state(
struct page *page,
int *delalloc,
int *unmapped,
int *unwritten)
{
struct buffer_head *bh, *head;
*delalloc = *unmapped = *unwritten = 0;
*delalloc = *unwritten = 0;
bh = head = page_buffers(page);
do {
if (buffer_uptodate(bh) && !buffer_mapped(bh))
(*unmapped) = 1;
else if (buffer_unwritten(bh))
if (buffer_unwritten(bh))
(*unwritten) = 1;
else if (buffer_delay(bh))
(*delalloc) = 1;
@ -607,31 +604,30 @@ xfs_map_at_offset(
STATIC unsigned int
xfs_probe_page(
struct page *page,
unsigned int pg_offset,
int mapped)
unsigned int pg_offset)
{
struct buffer_head *bh, *head;
int ret = 0;
if (PageWriteback(page))
return 0;
if (!PageDirty(page))
return 0;
if (!page->mapping)
return 0;
if (!page_has_buffers(page))
return 0;
if (page->mapping && PageDirty(page)) {
if (page_has_buffers(page)) {
struct buffer_head *bh, *head;
bh = head = page_buffers(page);
do {
if (!buffer_uptodate(bh))
break;
if (mapped != buffer_mapped(bh))
break;
ret += bh->b_size;
if (ret >= pg_offset)
break;
} while ((bh = bh->b_this_page) != head);
} else
ret = mapped ? 0 : PAGE_CACHE_SIZE;
}
bh = head = page_buffers(page);
do {
if (!buffer_uptodate(bh))
break;
if (!buffer_mapped(bh))
break;
ret += bh->b_size;
if (ret >= pg_offset)
break;
} while ((bh = bh->b_this_page) != head);
return ret;
}
@ -641,8 +637,7 @@ xfs_probe_cluster(
struct inode *inode,
struct page *startpage,
struct buffer_head *bh,
struct buffer_head *head,
int mapped)
struct buffer_head *head)
{
struct pagevec pvec;
pgoff_t tindex, tlast, tloff;
@ -651,7 +646,7 @@ xfs_probe_cluster(
/* First sum forwards in this page */
do {
if (!buffer_uptodate(bh) || (mapped != buffer_mapped(bh)))
if (!buffer_uptodate(bh) || !buffer_mapped(bh))
return total;
total += bh->b_size;
} while ((bh = bh->b_this_page) != head);
@ -685,7 +680,7 @@ xfs_probe_cluster(
pg_offset = PAGE_CACHE_SIZE;
if (page->index == tindex && trylock_page(page)) {
pg_len = xfs_probe_page(page, pg_offset, mapped);
pg_len = xfs_probe_page(page, pg_offset);
unlock_page(page);
}
@ -1021,18 +1016,12 @@ xfs_aops_discard_page(
* For delalloc space on the page we need to allocate space and flush it.
* For unwritten space on the page we need to start the conversion to
* regular allocated space.
* For unmapped buffer heads on the page we should allocate space if the
* page is uptodate.
* For any other dirty buffer heads on the page we should flush them.
*
* If we detect that a transaction would be required to flush the page, we
* have to check the process flags first, if we are already in a transaction
* or disk I/O during allocations is off, we need to fail the writepage and
* redirty the page.
*
* The bh->b_state's cannot know if any of the blocks or which block for that
* matter are dirty due to mmap writes, and therefore bh uptodate is only
* valid if the page itself isn't completely uptodate.
*/
STATIC int
xfs_vm_writepage(
@ -1040,8 +1029,7 @@ xfs_vm_writepage(
struct writeback_control *wbc)
{
struct inode *inode = page->mapping->host;
int need_trans;
int delalloc, unmapped, unwritten;
int delalloc, unwritten;
struct buffer_head *bh, *head;
struct xfs_bmbt_irec imap;
xfs_ioend_t *ioend = NULL, *iohead = NULL;
@ -1052,10 +1040,12 @@ xfs_vm_writepage(
ssize_t size, len;
int flags, err, imap_valid = 0, uptodate = 1;
int count = 0;
int all_bh;
int all_bh = 0;
trace_xfs_writepage(inode, page, 0);
ASSERT(page_has_buffers(page));
/*
* Refuse to write the page out if we are called from reclaim context.
*
@ -1072,29 +1062,15 @@ xfs_vm_writepage(
goto out_fail;
/*
* We need a transaction if:
* 1. There are delalloc buffers on the page
* 2. The page is uptodate and we have unmapped buffers
* 3. The page is uptodate and we have no buffers
* 4. There are unwritten buffers on the page
* We need a transaction if there are delalloc or unwritten buffers
* on the page.
*
* If we need a transaction and the process flags say we are already
* in a transaction, or no IO is allowed then mark the page dirty
* again and leave the page as is.
*/
if (!page_has_buffers(page)) {
unmapped = 1;
need_trans = 1;
} else {
xfs_count_page_state(page, &delalloc, &unmapped, &unwritten);
if (!PageUptodate(page))
unmapped = 0;
need_trans = delalloc + unmapped + unwritten;
}
/*
* If we need a transaction and the process flags say
* we are already in a transaction, or no IO is allowed
* then mark the page dirty again and leave the page
* as is.
*/
if (current_test_flags(PF_FSTRANS) && need_trans)
xfs_count_page_state(page, &delalloc, &unwritten);
if ((current->flags & PF_FSTRANS) && (delalloc || unwritten))
goto out_fail;
/*
@ -1117,7 +1093,8 @@ xfs_vm_writepage(
}
end_offset = min_t(unsigned long long,
(xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT, offset);
(xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
offset);
len = 1 << inode->i_blkbits;
bh = head = page_buffers(page);
@ -1125,8 +1102,6 @@ xfs_vm_writepage(
flags = BMAPI_READ;
type = IO_NEW;
all_bh = unmapped;
do {
if (offset >= end_offset)
break;
@ -1146,19 +1121,7 @@ xfs_vm_writepage(
if (imap_valid)
imap_valid = xfs_imap_valid(inode, &imap, offset);
/*
* First case, map an unwritten extent and prepare for
* extent state conversion transaction on completion.
*
* Second case, allocate space for a delalloc buffer.
* We can return EAGAIN here in the release page case.
*
* Third case, an unmapped buffer was found, and we are
* in a path where we need to write the whole page out.
*/
if (buffer_unwritten(bh) || buffer_delay(bh) ||
((buffer_uptodate(bh) || PageUptodate(page)) &&
!buffer_mapped(bh))) {
if (buffer_unwritten(bh) || buffer_delay(bh)) {
int new_ioend = 0;
/*
@ -1177,14 +1140,11 @@ xfs_vm_writepage(
if (wbc->sync_mode == WB_SYNC_NONE &&
wbc->nonblocking)
flags |= BMAPI_TRYLOCK;
} else {
type = IO_NEW;
flags = BMAPI_WRITE | BMAPI_MMAP;
}
if (!imap_valid) {
/*
* if we didn't have a valid mapping then we
* If we didn't have a valid mapping then we
* need to ensure that we put the new mapping
* in a new ioend structure. This needs to be
* done to ensure that the ioends correctly
@ -1192,14 +1152,7 @@ xfs_vm_writepage(
* for unwritten extent conversion.
*/
new_ioend = 1;
if (type == IO_NEW) {
size = xfs_probe_cluster(inode,
page, bh, head, 0);
} else {
size = len;
}
err = xfs_map_blocks(inode, offset, size,
err = xfs_map_blocks(inode, offset, len,
&imap, flags);
if (err)
goto error;
@ -1220,8 +1173,7 @@ xfs_vm_writepage(
*/
if (!imap_valid || flags != BMAPI_READ) {
flags = BMAPI_READ;
size = xfs_probe_cluster(inode, page, bh,
head, 1);
size = xfs_probe_cluster(inode, page, bh, head);
err = xfs_map_blocks(inode, offset, size,
&imap, flags);
if (err)
@ -1240,7 +1192,6 @@ xfs_vm_writepage(
*/
type = IO_NEW;
if (trylock_buffer(bh)) {
ASSERT(buffer_mapped(bh));
if (imap_valid)
all_bh = 1;
xfs_add_to_ioend(inode, bh, offset, type,
@ -1250,6 +1201,7 @@ xfs_vm_writepage(
imap_valid = 0;
}
} else if (PageUptodate(page)) {
ASSERT(buffer_mapped(bh));
imap_valid = 0;
}
@ -1291,8 +1243,7 @@ xfs_vm_writepage(
if (iohead)
xfs_cancel_ioend(iohead);
if (!unmapped)
xfs_aops_discard_page(page);
xfs_aops_discard_page(page);
ClearPageUptodate(page);
unlock_page(page);
return err;
@ -1324,11 +1275,11 @@ xfs_vm_releasepage(
struct page *page,
gfp_t gfp_mask)
{
int delalloc, unmapped, unwritten;
int delalloc, unwritten;
trace_xfs_releasepage(page->mapping->host, page, 0);
xfs_count_page_state(page, &delalloc, &unmapped, &unwritten);
xfs_count_page_state(page, &delalloc, &unwritten);
if (WARN_ON(delalloc))
return 0;

2
fs/xfs/linux-2.6/xfs_aops.h
View file

@ -45,6 +45,6 @@ extern int xfs_get_blocks(struct inode *, sector_t, struct buffer_head *, int);
extern void xfs_ioend_init(void);
extern void xfs_ioend_wait(struct xfs_inode *);
extern void xfs_count_page_state(struct page *, int *, int *, int *);
extern void xfs_count_page_state(struct page *, int *, int *);
#endif /* __XFS_AOPS_H__ */

10
fs/xfs/linux-2.6/xfs_trace.h
View file

@ -832,33 +832,29 @@ DECLARE_EVENT_CLASS(xfs_page_class,
__field(loff_t, size)
__field(unsigned long, offset)
__field(int, delalloc)
__field(int, unmapped)
__field(int, unwritten)
),
TP_fast_assign(
int delalloc = -1, unmapped = -1, unwritten = -1;
int delalloc = -1, unwritten = -1;
if (page_has_buffers(page))
xfs_count_page_state(page, &delalloc,
&unmapped, &unwritten);
xfs_count_page_state(page, &delalloc, &unwritten);
__entry->dev = inode->i_sb->s_dev;
__entry->ino = XFS_I(inode)->i_ino;
__entry->pgoff = page_offset(page);
__entry->size = i_size_read(inode);
__entry->offset = off;
__entry->delalloc = delalloc;
__entry->unmapped = unmapped;
__entry->unwritten = unwritten;
),
TP_printk("dev %d:%d ino 0x%llx pgoff 0x%lx size 0x%llx offset %lx "
"delalloc %d unmapped %d unwritten %d",
"delalloc %d unwritten %d",
MAJOR(__entry->dev), MINOR(__entry->dev),
__entry->ino,
__entry->pgoff,
__entry->size,
__entry->offset,
__entry->delalloc,
__entry->unmapped,
__entry->unwritten)
)