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btrfs: enumerate the type of exclusive operation in progress

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Instead of using a flag bit for exclusive operation, use a variable to
store which exclusive operation is being performed.  Introduce an API
to start and finish an exclusive operation.

This would enable another way for tools to check which operation is
running on why starting an exclusive operation failed. The followup
patch adds a sysfs_notify() to alert userspace when the state changes, so
userspace can perform select() on it to get notified of the change.

This would enable us to enqueue a command which will wait for current
exclusive operation to complete before issuing the next exclusive
operation. This has been done synchronously as opposed to a background
process, or else error collection (if any) will become difficult.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update comments ]
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Goldwyn Rodrigues
2020-08-25 10:02:32 -05:00
committed by David Sterba
parent ca10845a56
commit c3e1f96c37
5 changed files with 65 additions and 41 deletions
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20
fs/btrfs/volumes.c
View File

@@ -291,8 +291,8 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
* balance_mutex
*
*
* Exclusive operations, BTRFS_FS_EXCL_OP
* ======================================
* Exclusive operations
* ====================
*
* Maintains the exclusivity of the following operations that apply to the
* whole filesystem and cannot run in parallel.
@@ -318,11 +318,11 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
* - system power-cycle and filesystem mounted as read-only
* - filesystem or device errors leading to forced read-only
*
* BTRFS_FS_EXCL_OP flag is set and cleared using atomic operations.
* During the course of Paused state, the BTRFS_FS_EXCL_OP remains set.
* The status of exclusive operation is set and cleared atomically.
* During the course of Paused state, fs_info::exclusive_operation remains set.
* A device operation in Paused or Running state can be canceled or resumed
* either by ioctl (Balance only) or when remounted as read-write.
* BTRFS_FS_EXCL_OP flag is cleared when the device operation is canceled or
* The exclusive status is cleared when the device operation is canceled or
* completed.
*/
@@ -4033,7 +4033,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
/*
* rw_devices will not change at the moment, device add/delete/replace
* are excluded by EXCL_OP
* are exclusive
*/
num_devices = fs_info->fs_devices->rw_devices;
@@ -4169,7 +4169,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
if ((ret && ret != -ECANCELED && ret != -ENOSPC) ||
balance_need_close(fs_info)) {
reset_balance_state(fs_info);
clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
btrfs_exclop_finish(fs_info);
}
wake_up(&fs_info->balance_wait_q);
@@ -4180,7 +4180,7 @@ out:
reset_balance_state(fs_info);
else
kfree(bctl);
clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
btrfs_exclop_finish(fs_info);
return ret;
}
@@ -4282,7 +4282,7 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info)
* is in a paused state and must have fs_info::balance_ctl properly
* set up.
*/
if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags))
if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE))
btrfs_warn(fs_info,
"balance: cannot set exclusive op status, resume manually");
@@ -4364,7 +4364,7 @@ int btrfs_cancel_balance(struct btrfs_fs_info *fs_info)
if (fs_info->balance_ctl) {
reset_balance_state(fs_info);
clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
btrfs_exclop_finish(fs_info);
btrfs_info(fs_info, "balance: canceled");
}
}