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author | Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> | 2024-08-16 07:07:03 +0300 |
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committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2024-08-21 03:57:33 +0300 |
commit | 43aec4d01bd2ce961817a777b3846f8318f398e4 (patch) | |
tree | e61c5f725f21443984f5116c85a642ba5053f266 /fs/f2fs | |
parent | c7f114d864ac91515bb07ac271e9824a20f5ed95 (diff) | |
download | linux-43aec4d01bd2ce961817a777b3846f8318f398e4.tar.xz |
f2fs: check discard support for conventional zones
As the helper function f2fs_bdev_support_discard() shows, f2fs checks if
the target block devices support discard by calling
bdev_max_discard_sectors() and bdev_is_zoned(). This check works well
for most cases, but it does not work for conventional zones on zoned
block devices. F2fs assumes that zoned block devices support discard,
and calls __submit_discard_cmd(). When __submit_discard_cmd() is called
for sequential write required zones, it works fine since
__submit_discard_cmd() issues zone reset commands instead of discard
commands. However, when __submit_discard_cmd() is called for
conventional zones, __blkdev_issue_discard() is called even when the
devices do not support discard.
The inappropriate __blkdev_issue_discard() call was not a problem before
the commit 30f1e7241422 ("block: move discard checks into the ioctl
handler") because __blkdev_issue_discard() checked if the target devices
support discard or not. If not, it returned EOPNOTSUPP. After the
commit, __blkdev_issue_discard() no longer checks it. It always returns
zero and sets NULL to the given bio pointer. This NULL pointer triggers
f2fs_bug_on() in __submit_discard_cmd(). The BUG is recreated with the
commands below at the umount step, where /dev/nullb0 is a zoned null_blk
with 5GB total size, 128MB zone size and 10 conventional zones.
$ mkfs.f2fs -f -m /dev/nullb0
$ mount /dev/nullb0 /mnt
$ for ((i=0;i<5;i++)); do dd if=/dev/zero of=/mnt/test bs=65536 count=1600 conv=fsync; done
$ umount /mnt
To fix the BUG, avoid the inappropriate __blkdev_issue_discard() call.
When discard is requested for conventional zones, check if the device
supports discard or not. If not, return EOPNOTSUPP.
Fixes: 30f1e7241422 ("block: move discard checks into the ioctl handler")
Cc: stable@vger.kernel.org
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs')
-rw-r--r-- | fs/f2fs/segment.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 3aee71c9f3c6..ed070b9ef91b 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -1282,6 +1282,13 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi, wait_list, issued); return 0; } + + /* + * Issue discard for conventional zones only if the device + * supports discard. + */ + if (!bdev_max_discard_sectors(bdev)) + return -EOPNOTSUPP; } #endif |