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Date: Tue, 21 Jun 2022 16:49:23 -0400 From: Sasha Levin <sashal@...nel.org> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: Jan Kara <jack@...e.cz>, Theodore Ts'o <tytso@....edu>, Sasha Levin <sashal@...nel.org>, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org Subject: [PATCH AUTOSEL 5.18 17/22] ext4: improve write performance with disabled delalloc From: Jan Kara <jack@...e.cz> [ Upstream commit 8d5459c11f548131ce48b2fbf45cccc5c382558f ] When delayed allocation is disabled (either through mount option or because we are running low on free space), ext4_write_begin() allocates blocks with EXT4_GET_BLOCKS_IO_CREATE_EXT flag. With this flag extent merging is disabled and since ext4_write_begin() is called for each page separately, we end up with a *lot* of 1 block extents in the extent tree and following writeback is writing 1 block at a time which results in very poor write throughput (4 MB/s instead of 200 MB/s). These days when ext4_get_block_unwritten() is used only by ext4_write_begin(), ext4_page_mkwrite() and inline data conversion, we can safely allow extent merging to happen from these paths since following writeback will happen on different boundaries anyway. So use EXT4_GET_BLOCKS_CREATE_UNRIT_EXT instead which restores the performance. Signed-off-by: Jan Kara <jack@...e.cz> Link: https://lore.kernel.org/r/20220520111402.4252-1-jack@suse.cz Signed-off-by: Theodore Ts'o <tytso@....edu> Signed-off-by: Sasha Levin <sashal@...nel.org> --- fs/ext4/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index beed9e32571c..767528daecb5 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -822,7 +822,7 @@ int ext4_get_block_unwritten(struct inode *inode, sector_t iblock, ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n", inode->i_ino, create); return _ext4_get_block(inode, iblock, bh_result, - EXT4_GET_BLOCKS_IO_CREATE_EXT); + EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT); } /* Maximum number of blocks we map for direct IO at once. */ -- 2.35.1
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