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ext4: use locality group preallocation for small closed files 

commit a9f2a2931d upstream.

Curently we don't use any preallocation when a file is already closed
when allocating blocks (from writeback code when converting delayed
allocation). However for small files, using locality group preallocation
is actually desirable as that is not specific to a particular file.
Rather it is a method to pack small files together to reduce
fragmentation and for that the fact the file is closed is actually even
stronger hint the file would benefit from packing. So change the logic
to allow locality group preallocation in this case.

Fixes: 196e402adf ("ext4: improve cr 0 / cr 1 group scanning")
CC: stable@kernel.org
Reported-and-tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/all/0d81a7c2-46b7-6010-62a4-3e6cfc1628d6@i2se.com/
Link: https://lore.kernel.org/r/20220908092136.11770-4-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Kara 2022-09-08 11:21:27 +02:00 committed by Greg Kroah-Hartman
parent 8a1ac4167d
commit 214194610a
1 changed files with 15 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
fs/ext4/mballoc.c
View File

@ -5169,6 +5169,7 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
int bsbits = ac->ac_sb->s_blocksize_bits;
loff_t size, isize;
bool inode_pa_eligible, group_pa_eligible;
if (!(ac->ac_flags & EXT4_MB_HINT_DATA))
return;
@ -5176,25 +5177,27 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
if (unlikely(ac->ac_flags & EXT4_MB_HINT_GOAL_ONLY))
return;
group_pa_eligible = sbi->s_mb_group_prealloc > 0;
inode_pa_eligible = true;
size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len);
isize = (i_size_read(ac->ac_inode) + ac->ac_sb->s_blocksize - 1)
>> bsbits;
/* No point in using inode preallocation for closed files */
if ((size == isize) && !ext4_fs_is_busy(sbi) &&
!inode_is_open_for_write(ac->ac_inode)) {
ac->ac_flags |= EXT4_MB_HINT_NOPREALLOC;
return;
}
!inode_is_open_for_write(ac->ac_inode))
inode_pa_eligible = false;
if (sbi->s_mb_group_prealloc <= 0) {
ac->ac_flags |= EXT4_MB_STREAM_ALLOC;
return;
}
/* don't use group allocation for large files */
size = max(size, isize);
if (size > sbi->s_mb_stream_request) {
ac->ac_flags |= EXT4_MB_STREAM_ALLOC;
/* Don't use group allocation for large files */
if (size > sbi->s_mb_stream_request)
group_pa_eligible = false;
if (!group_pa_eligible) {
if (inode_pa_eligible)
ac->ac_flags |= EXT4_MB_STREAM_ALLOC;
else
ac->ac_flags |= EXT4_MB_HINT_NOPREALLOC;
return;
}