linux.git/fs/btrfs/dev-replace.c, branch v6.3

btrfs: use btrfs_dev_name() helper to handle missing devices better

2022-12-05T17:00:57+00:00

[BUG]
If dev-replace failed to re-construct its data/metadata, the kernel
message would be incorrect for the missing device:

 BTRFS info (device dm-1): dev_replace from  (devid 2) to /dev/mapper/test-scratch2 started
 BTRFS error (device dm-1): failed to rebuild valid logical 38862848 for dev (efault)

Note the above "dev (efault)" of the second line.
While the first line is properly reporting "".

[CAUSE]
Although dev-replace is using btrfs_dev_name(), the heavy lifting work
is still done by scrub (scrub is reused by both dev-replace and regular
scrub).

Unfortunately scrub code never uses btrfs_dev_name() helper, as it's
only declared locally inside dev-replace.c.

[FIX]
Fix the output by:

- Move the btrfs_dev_name() helper to volumes.h

- Use btrfs_dev_name() to replace open-coded rcu_str_deref() calls
  Only zoned code is not touched, as I'm not familiar with degraded
  zoned code.

- Constify return value and parameter

Now the output looks pretty sane:

 BTRFS info (device dm-1): dev_replace from  (devid 2) to /dev/mapper/test-scratch2 started
 BTRFS error (device dm-1): failed to rebuild valid logical 38862848 for dev 

Reviewed-by: Anand Jain 
Signed-off-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: move device->name RCU allocation and assign to btrfs_alloc_device()

2022-12-05T17:00:55+00:00

There is a repeating code section in the parent function after calling
btrfs_alloc_device(), as below:

      name = rcu_string_strdup(path, GFP_...);
      if (!name) {
              btrfs_free_device(device);
              return ERR_PTR(-ENOMEM);
      }
      rcu_assign_pointer(device->name, name);

Except in add_missing_dev() for obvious reasons.

This patch consolidates that repeating code into the btrfs_alloc_device()
itself so that the parent function doesn't have to duplicate code.
This consolidation also helps to review issues regarding RCU lock
violation with device->name.

Parent function device_list_add() and add_missing_dev() use GFP_NOFS for
the allocation, whereas the rest of the parent functions use GFP_KERNEL,
so bring the NOFS allocation context using memalloc_nofs_save() in the
function device_list_add() and add_missing_dev() is already doing it.

Signed-off-by: Anand Jain 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: move scrub prototypes into scrub.h

2022-12-05T17:00:47+00:00

Move these out of ctree.h into scrub.h to cut down on code in ctree.h.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Josef Bacik 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: move accessor helpers into accessors.h

2022-12-05T17:00:42+00:00

This is a large patch, but because they're all macros it's impossible to
split up.  Simply copy all of the item accessors in ctree.h and paste
them in accessors.h, and then update any files to include the header so
everything compiles.

Reviewed-by: Anand Jain 
Signed-off-by: Josef Bacik 
Reviewed-by: David Sterba 
[ reformat comments, style fixups ]
Signed-off-by: David Sterba

btrfs: move BTRFS_FS_STATE* definitions and helpers to fs.h

2022-12-05T17:00:42+00:00

We're going to use fs.h to hold fs wide related helpers and definitions,
move the FS_STATE enum and related helpers to fs.h, and then update all
files that need these definitions to include fs.h.

Reviewed-by: Johannes Thumshirn 
Reviewed-by: Anand Jain 
Signed-off-by: Josef Bacik 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: don't take a bio_counter reference for cloned bios

2022-09-26T10:27:58+00:00

Stop grabbing an extra bio_counter reference for each clone bio in a
mirrored write and instead just release the one original reference in
btrfs_end_bioc once all the bios for a single btrfs_bio have completed
instead of at the end of btrfs_submit_bio once all bios have been
submitted.

This means the reference is now carried by the "upper" btrfs_bio only
instead of each lower bio.

Also remove the now unused btrfs_bio_counter_inc_noblocked helper.

Reviewed-by: Nikolay Borisov 
Reviewed-by: Johannes Thumshirn 
Reviewed-by: Anand Jain 
Signed-off-by: Christoph Hellwig 
Signed-off-by: David Sterba

btrfs: remove lock protection for BLOCK_GROUP_FLAG_TO_COPY

2022-09-26T10:27:54+00:00

We use this during device replace for zoned devices, we were simply
taking the lock because it was in a bit field and we needed the lock to
be safe with other modifications in the bitfield.  With the bit helpers
we no longer require that locking.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Josef Bacik 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: convert block group bit field to use bit helpers

2022-09-26T10:27:54+00:00

We use a bit field in the btrfs_block_group for different flags, however
this is awkward because we have to hold the block_group->lock for any
modification of any of these fields, and makes the code clunky for a few
of these flags.  Convert these to a properly flags setup so we can
utilize the bit helpers.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Josef Bacik 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: add info when mount fails due to stale replace target

2022-08-23T20:15:21+00:00

If the replace target device reappears after the suspended replace is
cancelled, it blocks the mount operation as it can't find the matching
replace-item in the metadata. As shown below,

   BTRFS error (device sda5): replace devid present without an active replace item

To overcome this situation, the user can run the command

   btrfs device scan --forget 

and try the mount command again. And also, to avoid repeating the issue,
superblock on the devid=0 must be wiped.

   wipefs -a device-path-to-devid=0.

This patch adds some info when this situation occurs.

Reported-by: Samuel Greiner 
Link: https://lore.kernel.org/linux-btrfs/b4f62b10-b295-26ea-71f9-9a5c9299d42c@balkonien.org/T/
CC: stable@vger.kernel.org # 5.0+
Signed-off-by: Anand Jain 
Signed-off-by: David Sterba

btrfs: replace: drop assert for suspended replace

2022-08-23T20:15:21+00:00

If the filesystem mounts with the replace-operation in a suspended state
and try to cancel the suspended replace-operation, we hit the assert. The
assert came from the commit fe97e2e173af ("btrfs: dev-replace: replace's
scrub must not be running in suspended state") that was actually not
required. So just remove it.

 $ mount /dev/sda5 /btrfs

    BTRFS info (device sda5): cannot continue dev_replace, tgtdev is missing
    BTRFS info (device sda5): you may cancel the operation after 'mount -o degraded'

 $ mount -o degraded /dev/sda5 /btrfs <-- success.

 $ btrfs replace cancel /btrfs

    kernel: assertion failed: ret != -ENOTCONN, in fs/btrfs/dev-replace.c:1131
    kernel: ------------[ cut here ]------------
    kernel: kernel BUG at fs/btrfs/ctree.h:3750!

After the patch:

 $ btrfs replace cancel /btrfs

    BTRFS info (device sda5): suspended dev_replace from /dev/sda5 (devid 1) to  canceled

Fixes: fe97e2e173af ("btrfs: dev-replace: replace's scrub must not be running in suspended state")
CC: stable@vger.kernel.org # 5.0+
Signed-off-by: Anand Jain 
Signed-off-by: David Sterba