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authorTheodore Ts'o <tytso@mit.edu>2011-02-26 14:09:14 -0500
committerTheodore Ts'o <tytso@mit.edu>2011-02-26 14:09:14 -0500
commit78aaced3408141bb7c836f2db0ca435790399da5 (patch)
treec761d397605095d4d895ede9fc5e6a6548723cad /fs/ext4
parentee6ecbcc5d73672217fdea420d182ecb0cdf310c (diff)
downloadop-kernel-dev-78aaced3408141bb7c836f2db0ca435790399da5.zip
op-kernel-dev-78aaced3408141bb7c836f2db0ca435790399da5.tar.gz
ext4: don't lock the next page in write_cache_pages if not needed
If we have accumulated a contiguous region of memory to be written out, and the next page can added to this region, don't bother locking (and then unlocking the page) before writing out the memory. In the unlikely event that the next page was being written back by some other CPU, we can also skip waiting that page to finish writeback. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/inode.c27
1 files changed, 10 insertions, 17 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 617c9cb..c2e6af3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2761,6 +2761,16 @@ static int write_cache_pages_da(struct address_space *mapping,
*done_index = page->index + 1;
+ /*
+ * If we can't merge this page, and we have
+ * accumulated an contiguous region, write it
+ */
+ if ((mpd->next_page != page->index) &&
+ (mpd->next_page != mpd->first_page)) {
+ mpage_da_map_and_submit(mpd);
+ goto ret_extent_tail;
+ }
+
lock_page(page);
/*
@@ -2784,25 +2794,8 @@ static int write_cache_pages_da(struct address_space *mapping,
BUG_ON(PageWriteback(page));
- /*
- * Can we merge this page to current extent?
- */
if (mpd->next_page != page->index) {
/*
- * Nope, we can't. So, we map
- * non-allocated blocks and start IO
- * on them
- */
- if (mpd->next_page != mpd->first_page) {
- mpage_da_map_and_submit(mpd);
- /*
- * skip rest of the page in the page_vec
- */
- unlock_page(page);
- goto ret_extent_tail;
- }
-
- /*
* Start next extent of pages and blocks
*/
mpd->first_page = page->index;
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