Patch "ext4: improve write performance with disabled delalloc" has been added to the 5.10-stable tree

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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 5.10-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-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5660cc0ca1a19b62ddee69191ffcb7d81606873d
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 365c4d3a434ab..045f0efb696ad 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -821,7 +821,7 @@ 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. */



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