xfs: simplify xfs_vm_writepage
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>
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 7744a3b..1776cdd 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -85,18 +85,15 @@
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 @@
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 @@
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 @@
/* 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 @@
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 @@
* 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 @@
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 @@
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 @@
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 @@
}
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 @@
flags = BMAPI_READ;
type = IO_NEW;
- all_bh = unmapped;
-
do {
if (offset >= end_offset)
break;
@@ -1146,19 +1121,7 @@
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 @@
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 @@
* 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 @@
*/
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 @@
*/
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 @@
imap_valid = 0;
}
} else if (PageUptodate(page)) {
+ ASSERT(buffer_mapped(bh));
imap_valid = 0;
}
@@ -1291,8 +1243,7 @@
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 @@
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;
diff --git a/fs/xfs/linux-2.6/xfs_aops.h b/fs/xfs/linux-2.6/xfs_aops.h
index 4cfc6ea..319da17 100644
--- a/fs/xfs/linux-2.6/xfs_aops.h
+++ b/fs/xfs/linux-2.6/xfs_aops.h
@@ -45,6 +45,6 @@
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__ */
diff --git a/fs/xfs/linux-2.6/xfs_trace.h b/fs/xfs/linux-2.6/xfs_trace.h
index 0aea6d5f..3f2eec2 100644
--- a/fs/xfs/linux-2.6/xfs_trace.h
+++ b/fs/xfs/linux-2.6/xfs_trace.h
@@ -832,33 +832,29 @@
__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)
)
