linux.git/fs/btrfs/dev-replace.c, branch v4.20

btrfs: dev-replace: remove pointless assert in write unlock

2018-10-15T15:23:38+00:00

The value of blocking_readers is increased only when the lock is taken
for read, no way we can fail the condition with the write lock.

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

btrfs: dev-replace: move replace members out of fs_info

2018-10-15T15:23:38+00:00

The replace_wait and bio_counter were mistakenly added to fs_info in
commit c404e0dc2c843b154f ("Btrfs: fix use-after-free in the finishing
procedure of the device replace"), but they logically belong to
fs_info::dev_replace. Besides, bio_counter is a very generic name and is
confusing in bare fs_info context.

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

btrfs: dev-replace: avoid useless lock on error handling path

2018-10-15T15:23:38+00:00

The exit sequence in btrfs_dev_replace_start does not allow to simply
add a label to the right place so the error handling after starting
transaction failure jumps there. Currently there's a lock that pairs
with the unlock in the section, which is unnecessary and only raises
questions.  Add a variable to track the locking status and avoid the
extra locking.

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

btrfs: open code btrfs_after_dev_replace_commit

2018-10-15T15:23:37+00:00

Too trivial, the purpose can be simply documented in a comment.

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

btrfs: open code btrfs_dev_replace_clear_lock_blocking

2018-10-15T15:23:37+00:00

There's a single caller and the function name does not say it's actually
taking the lock, so open coding makes it more explicit.

For now, btrfs_dev_replace_read_lock is used instead of read_lock so
it's paired with the unlocking wrapper in the same block.

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

btrfs: remove btrfs_dev_replace::read_locks

2018-10-15T15:23:37+00:00

This member seems to be copied from the extent_buffer locking scheme and
is at least used to assert that the read lock/unlock is properly nested.
In some way. While the _inc/_dec are called inside the read lock
section, the asserts are both inside and outside, so the ordering is not
guaranteed and we can see read/inc/dec ordered in any way
(theoretically).

A missing call of btrfs_dev_replace_clear_lock_blocking could cause
unexpected read_locks count, so this at least looks like a valid
assertion, but this will become unnecessary with later updates.

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

btrfs: fix error handling in btrfs_dev_replace_start

2018-10-15T15:23:31+00:00

When we fail to start a transaction in btrfs_dev_replace_start, we leave
dev_replace->replace_start set to STARTED but clear ->srcdev and
->tgtdev.  Later, that can result in an Oops in
btrfs_dev_replace_progress when having state set to STARTED or SUSPENDED
implies that ->srcdev is valid.

Also fix error handling when the state is already STARTED or SUSPENDED
while starting.  That, too, will clear ->srcdev and ->tgtdev even though
it doesn't own them.  This should be an impossible case to hit since we
should be protected by the BTRFS_FS_EXCL_OP bit being set.  Let's add an
ASSERT there while we're at it.

Fixes: e93c89c1aaaaa (Btrfs: add new sources for device replace code)
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Jeff Mahoney 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Make btrfs_find_device_by_devspec return btrfs_device directly

2018-10-15T15:23:30+00:00

Instead of returning an error value and using one of the parameters for
returning the actual object we are interested in just refactor the
function to directly return btrfs_device *. Also bubble up the error
handling for the special BTRFS_ERROR_DEV_MISSING_NOT_FOUND value into
btrfs_rm_device. No functional changes.

Signed-off-by: Nikolay Borisov 
Reviewed-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: replace: Reset on-disk dev stats value after replace

2018-08-06T11:13:01+00:00

on-disk devs stats value is updated in btrfs_run_dev_stats(),
which is called during commit transaction, if device->dev_stats_ccnt
is not zero.

Since current replace operation does not touch dev_stats_ccnt,
on-disk dev stats value is not updated. Therefore "btrfs device stats"
may return old device's value after umount/mount
(Example: See "btrfs ins dump-t -t DEV $DEV" after btrfs/100 finish).

Fix this by just incrementing dev_stats_ccnt in
btrfs_dev_replace_finishing() when replace is succeeded and this will
update the values.

Signed-off-by: Misono Tomohiro 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Remove fs_info from btrfs_destroy_dev_replace_tgtdev

2018-08-06T11:12:57+00:00

This function is always passed a well-formed tgtdevice so the fs_info
can be referenced from there.

Signed-off-by: Nikolay Borisov 
Reviewed-by: Lu Fengqi 
Signed-off-by: David Sterba