2.6.22-stable review patch. If anyone has any objections, please let us know. ------------------ From: Mark Fasheh 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 Signed-off-by: Greg Kroah-Hartman --- fs/ocfs2/aops.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) --- a/fs/ocfs2/aops.c +++ b/fs/ocfs2/aops.c @@ -661,6 +661,27 @@ static void ocfs2_clear_page_regions(str } /* + * 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 *p 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; } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/