linux.git/fs/btrfs/dev-replace.c, branch v5.4

btrfs: move cond_wake_up functions out of ctree

2019-09-09T12:59:15+00:00

The file ctree.h serves as a header for everything and has become quite
bloated. Split some helpers that are generic and create a new file that
should be the catch-all for code that's not btrfs-specific.

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

btrfs: replace: BTRFS_DEV_REPLACE_ITEM_STATE_x defines should go

2019-09-09T12:59:11+00:00

The BTRFS_DEV_REPLACE_ITEM_STATE_x defines, as shown in [1], are
unused in both kernel and btrfs-progs (except for one instance of
BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED in kernel).

[1]
btrfs.h:#define BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED        2
btrfs.h:#define BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED        3
btrfs.h:#define BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED       4

Further these define-values are different form its counterpart
BTRFS_IOCTL_DEV_REPLACE_STATE_x series as shown in [2].

[2]
btrfs_tree.h:#define BTRFS_DEV_REPLACE_ITEM_STATE_SUSPENDED   2
btrfs_tree.h:#define BTRFS_DEV_REPLACE_ITEM_STATE_FINISHED    3
btrfs_tree.h:#define BTRFS_DEV_REPLACE_ITEM_STATE_CANCELED    4

So this patch deletes the BTRFS_DEV_REPLACE_ITEM_STATE_x altogether, and
one instance of BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED is replaced
with BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED in the kernel.

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

btrfs: remove mapping tree structures indirection

2019-07-01T11:34:56+00:00

fs_info::mapping_tree is the physical<->logical mapping tree and uses
the same underlying structure as extents, but is embedded to another
structure. There are no other members and this indirection is useless.
No functional change.

Signed-off-by: David Sterba

btrfs: Remove redundant assignment of tgt_device->commit_total_bytes

2019-07-01T11:34:55+00:00

This is already done in btrfs_init_dev_replace_tgtdev which is the first
phase of device replace, called before doing scrub. During that time
exclusive lock is held. Additionally btrfs_fs_device::commit_total_bytes
is always set based on the size of the underlying block device which
shouldn't change once set. This makes the 2nd assignment of the variable
in the finishing phase redundant.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Explicitly reserve space for devreplace item

2019-07-01T11:34:54+00:00

Part of device replace involves writing an item to the device root
containing information about pending replace operations. Currently space
for this item is not being explicitly reserved so this works thanks to
presence of global reserve. While not fatal it's not a good practice.
Let's be explicit about space requirement of device replace and reserve
space when starting the transaction.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Streamline replace sem unlock in btrfs_dev_replace_start

2019-07-01T11:34:54+00:00

There are only 2 branches which goto leave label with need_unlock set
to true. Essentially need_unlock is used as a substitute for directly
calling up_write. Since the branches needing this are only 2 and their
context is not that big it's more clear to just call up_write where
required. No functional changes.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Ensure btrfs_init_dev_replace_tgtdev sees up to date values

2019-07-01T11:34:54+00:00

btrfs_init_dev_replace_tgtdev reads certain values from the source
device (such as commit_total_bytes) which are updated during transaction
commit. Currently this function is called before committing any pending
transaction, leading to possibly reading outdated values.

Fix this by moving the function below the transaction commit, at this
point the EXCL_OP bit it set hence once transaction is complete the
total size of the device cannot be changed (it's usually changed by
resize/remove ops which are blocked).

Fixes: 9e271ae27e44 ("Btrfs: kernel operation should come after user input has been verified")
Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: dev-replace: Remove impossible WARN_ON

2019-07-01T11:34:54+00:00

This WARN_ON can never trigger because src_device cannot be null.
btrfs_find_device_by_devspec always returns either an error or a valid
pointer to the device. Just remove it.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Reduce critical section in btrfs_init_dev_replace_tgtdev

2019-07-01T11:34:54+00:00

There is no point in holding btrfs_fs_devices::device_list_mutex
while initialising fields of the not-yet-published device. Instead,
hold the mutex only when the newly initialised device is being
published. I think holding device_list_mutex here is redundant
altogether, because at this point BTRFS_FS_EXCL_OP is set which
prevents device removal/addition/balance/resize to occur.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: Don't opencode sync_blockdev in btrfs_init_dev_replace_tgtdev

2019-07-01T11:34:53+00:00

Using sync_blockdev makes it plain obvious what's happening. No
functional changes.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba