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author | Mark Fasheh <mark.fasheh@oracle.com> | 2007-11-14 13:33:27 -0800 |
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committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-11-21 09:25:56 -0800 |
commit | 2e95672cd8684beddb2390ed5212ac50e1fd0dae (patch) | |
tree | 301501efe5bee4d262c6d09e8b4f060c6236ce42 | |
parent | 0b81a81aecb120cff349eec24c2553e88c94991c (diff) | |
download | lwn-2e95672cd8684beddb2390ed5212ac50e1fd0dae.tar.gz lwn-2e95672cd8684beddb2390ed5212ac50e1fd0dae.zip |
ocfs2: fix write() performance regression
ocfs2: fix write() performance regression
patch 4e9563fd55ff4479f2b118d0757d121dd0cfc39c in mainline.
On file systems which don't support sparse files, Ocfs2_map_page_blocks()
was reading blocks on appending writes. This caused write performance to
suffer dramatically. Fix this by detecting an appending write on a nonsparse
fs and skipping the read.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r-- | fs/ocfs2/aops.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c index a480b09c79b9..3175288a10ca 100644 --- a/fs/ocfs2/aops.c +++ b/fs/ocfs2/aops.c @@ -661,6 +661,27 @@ static void ocfs2_clear_page_regions(struct page *page, } /* + * Nonsparse file systems fully allocate before we get to the write + * code. This prevents ocfs2_write() from tagging the write as an + * allocating one, which means ocfs2_map_page_blocks() might try to + * read-in the blocks at the tail of our file. Avoid reading them by + * testing i_size against each block offset. + */ +static int ocfs2_should_read_blk(struct inode *inode, struct page *page, + unsigned int block_start) +{ + u64 offset = page_offset(page) + block_start; + + if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) + return 1; + + if (i_size_read(inode) > offset) + return 1; + + return 0; +} + +/* * Some of this taken from block_prepare_write(). We already have our * mapping by now though, and the entire write will be allocating or * it won't, so not much need to use BH_New. @@ -711,7 +732,8 @@ int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno, if (!buffer_uptodate(bh)) set_buffer_uptodate(bh); } else if (!buffer_uptodate(bh) && !buffer_delay(bh) && - (block_start < from || block_end > to)) { + ocfs2_should_read_blk(inode, page, block_start) && + (block_start < from || block_end > to)) { ll_rw_block(READ, 1, &bh); *wait_bh++=bh; } |