This is a note to let you know that I've just added the patch titled
ext4: improve write performance with disabled delalloc
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-improve-write-performance-with-disabled-delallo.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b761964a221739a6175a704f4e3304bd8b809f3f
Author: Jan Kara <jack@xxxxxxx>
Date: Fri May 20 13:14:02 2022 +0200
ext4: improve write performance with disabled delalloc
[ 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@xxxxxxx>
Link: https://lore.kernel.org/r/20220520111402.4252-1-jack@xxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Stable-dep-of: 2cd8bdb5efc1 ("ext4: mark buffer new if it is unwritten to avoid stale data exposure")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8a0bca3b653bc..9ca7db0c4039a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -830,7 +830,7 @@ 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. */
