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btrfs: iterate all devices during trim, instead of fs_devices::alloc_list

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commit d4e329de5e5e21594df2e0dd59da9acee71f133b upstream.

btrfs_trim_fs iterates over the fs_devices->alloc_list while holding the
device_list_mutex.  The problem is that ->alloc_list is protected by the
chunk mutex.  We don't want to hold the chunk mutex over the trim of the
entire file system.  Fortunately, the ->dev_list list is protected by
the dev_list mutex and while it will give us all devices, including
read-only devices, we already just skip the read-only devices.  Then we
can continue to take and release the chunk mutex while scanning each
device.

Fixes: 499f377f49f ("btrfs: iterate over unused chunk space in FITRIM")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jeff Mahoney 2018-09-06 17:18:14 -04:00 committed by Greg Kroah-Hartman
parent 1bd7112bb9
commit d87af98c5a
1 changed files with 2 additions and 2 deletions
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4
fs/btrfs/extent-tree.c
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@ -11193,8 +11193,8 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
}
mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
devices = &root->fs_info->fs_devices->alloc_list;
list_for_each_entry(device, devices, dev_alloc_list) {
devices = &root->fs_info->fs_devices->devices;
list_for_each_entry(device, devices, dev_list) {
ret = btrfs_trim_free_extents(device, range->minlen,
&group_trimmed);
if (ret)