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A cascade of MD reverts occurred late in the v5.10-rcX cycle due to MD 

raid10 discard optimizations having introduced potential for
 corruption. Those reverts exposed a dm-raid.c compiler warning that
 wasn't ever knowingly introduced. That min_not_zero() type mismatch
 warning was thought to be safely fixed simply by changing 'struct
 mddev' to use 'unsigned int' rather than int for chunk_sectors members
 in that struct. I proposed either using a cast local to dm-raid.c but
 thought changing the type to 'unsigned int' more correct. While that
 may be, not enough testing was paired with code review associated with
 making that change. As such we were left exposed and the result was a
 report that with v5.10 btrfs on MD RAID6 failed to mount:
 https://lkml.org/lkml/2020/12/14/7
 
 Given that report, it is justified to simply revert these offending
 commits. stable@ has already taken steps to revert these for 5.10.1 -
 this pull request just makes sure mainline does so too.
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Merge tag 'for-5.11/revert-problem-v5.10-raid-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull MD regression reverts from Mike Snitzer:
 "A cascade of MD reverts occurred late in the v5.10-rcX cycle due to MD
  raid10 discard optimizations having introduced potential for
  corruption.

  Those reverts exposed a dm-raid.c compiler warning that wasn't ever
  knowingly introduced. That min_not_zero() type mismatch warning was
  thought to be safely fixed simply by changing 'struct mddev' to use
  'unsigned int' rather than int for chunk_sectors members in that
  struct.

  I proposed either using a cast local to dm-raid.c but thought changing
  the type to 'unsigned int' more correct. While that may be, not enough
  testing was paired with code review associated with making that
  change. As such we were left exposed and the result was a report that
  with v5.10 btrfs on MD RAID6 failed to mount:

    https://lkml.org/lkml/2020/12/14/7

  Given that report, it is justified to simply revert these offending
  commits. stable@ has already taken steps to revert these for 5.10.1 -
  this just makes sure mainline does so too"

* tag 'for-5.11/revert-problem-v5.10-raid-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  Revert "dm raid: fix discard limits for raid1 and raid10"
  Revert "md: change mddev 'chunk_sectors' from int to unsigned"
This commit is contained in:
Linus Torvalds 2020-12-14 11:27:46 -08:00
parent bcc68bd816 0941e3b065
commit ae1985b50a
2 changed files with 7 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/md/dm-raid.c
View File

@ -3730,14 +3730,12 @@ static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
blk_limits_io_opt(limits, chunk_size_bytes * mddev_data_stripes(rs));
/*
* RAID10 personality requires bio splitting,
* RAID0/1/4/5/6 don't and process large discard bios properly.
* RAID1 and RAID10 personalities require bio splitting,
* RAID0/4/5/6 don't and process large discard bios properly.
*/
if (rs_is_raid10(rs)) {
limits->discard_granularity = max(chunk_size_bytes,
limits->discard_granularity);
limits->max_discard_sectors = min_not_zero(rs->md.chunk_sectors,
limits->max_discard_sectors);
if (rs_is_raid1(rs) || rs_is_raid10(rs)) {
limits->discard_granularity = chunk_size_bytes;
limits->max_discard_sectors = rs->md.chunk_sectors;
}
}

4
drivers/md/md.h
View File

@ -311,7 +311,7 @@ struct mddev {
int external; /* metadata is
* managed externally */
char metadata_type[17]; /* externally set*/
unsigned int chunk_sectors;
int chunk_sectors;
time64_t ctime, utime;
int level, layout;
char clevel[16];
@ -339,7 +339,7 @@ struct mddev {
*/
sector_t reshape_position;
int delta_disks, new_level, new_layout;
unsigned int new_chunk_sectors;
int new_chunk_sectors;
int reshape_backwards;
struct md_thread *thread; /* management thread */