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btrfs: use btrfs_get_dev_args_from_path in dev removal ioctls
For device removal and replace we call btrfs_find_device_by_devspec, which if we give it a device path and nothing else will call btrfs_get_dev_args_from_path, which opens the block device and reads the super block and then looks up our device based on that. However at this point we're holding the sb write "lock", so reading the block device pulls in the dependency of ->open_mutex, which produces the following lockdep splat ====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc2+ #405 Not tainted ------------------------------------------------------ losetup/11576 is trying to acquire lock: ffff9bbe8cded938 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x67/0x5e0 but task is already holding lock: ffff9bbe88e4fc68 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x660 [loop] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&lo->lo_mutex){+.+.}-{3:3}: __mutex_lock+0x7d/0x750 lo_open+0x28/0x60 [loop] blkdev_get_whole+0x25/0xf0 blkdev_get_by_dev.part.0+0x168/0x3c0 blkdev_open+0xd2/0xe0 do_dentry_open+0x161/0x390 path_openat+0x3cc/0xa20 do_filp_open+0x96/0x120 do_sys_openat2+0x7b/0x130 __x64_sys_openat+0x46/0x70 do_syscall_64+0x38/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #3 (&disk->open_mutex){+.+.}-{3:3}: __mutex_lock+0x7d/0x750 blkdev_get_by_dev.part.0+0x56/0x3c0 blkdev_get_by_path+0x98/0xa0 btrfs_get_bdev_and_sb+0x1b/0xb0 btrfs_find_device_by_devspec+0x12b/0x1c0 btrfs_rm_device+0x127/0x610 btrfs_ioctl+0x2a31/0x2e70 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x38/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #2 (sb_writers#12){.+.+}-{0:0}: lo_write_bvec+0xc2/0x240 [loop] loop_process_work+0x238/0xd00 [loop] process_one_work+0x26b/0x560 worker_thread+0x55/0x3c0 kthread+0x140/0x160 ret_from_fork+0x1f/0x30 -> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}: process_one_work+0x245/0x560 worker_thread+0x55/0x3c0 kthread+0x140/0x160 ret_from_fork+0x1f/0x30 -> #0 ((wq_completion)loop0){+.+.}-{0:0}: __lock_acquire+0x10ea/0x1d90 lock_acquire+0xb5/0x2b0 flush_workqueue+0x91/0x5e0 drain_workqueue+0xa0/0x110 destroy_workqueue+0x36/0x250 __loop_clr_fd+0x9a/0x660 [loop] block_ioctl+0x3f/0x50 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x38/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: (wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&lo->lo_mutex); lock(&disk->open_mutex); lock(&lo->lo_mutex); lock((wq_completion)loop0); *** DEADLOCK *** 1 lock held by losetup/11576: #0: ffff9bbe88e4fc68 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x660 [loop] stack backtrace: CPU: 0 PID: 11576 Comm: losetup Not tainted 5.14.0-rc2+ #405 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 Call Trace: dump_stack_lvl+0x57/0x72 check_noncircular+0xcf/0xf0 ? stack_trace_save+0x3b/0x50 __lock_acquire+0x10ea/0x1d90 lock_acquire+0xb5/0x2b0 ? flush_workqueue+0x67/0x5e0 ? lockdep_init_map_type+0x47/0x220 flush_workqueue+0x91/0x5e0 ? flush_workqueue+0x67/0x5e0 ? verify_cpu+0xf0/0x100 drain_workqueue+0xa0/0x110 destroy_workqueue+0x36/0x250 __loop_clr_fd+0x9a/0x660 [loop] ? blkdev_ioctl+0x8d/0x2a0 block_ioctl+0x3f/0x50 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x38/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f31b02404cb Instead what we want to do is populate our device lookup args before we grab any locks, and then pass these args into btrfs_rm_device(). From there we can find the device and do the appropriate removal. Suggested-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik
David Sterba
parent
faa775c41d
commit
1a15eb724a
@ -3160,6 +3160,7 @@ out:
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static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
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{
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BTRFS_DEV_LOOKUP_ARGS(args);
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struct inode *inode = file_inode(file);
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struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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struct btrfs_ioctl_vol_args_v2 *vol_args;
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@ -3171,35 +3172,39 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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ret = mnt_want_write_file(file);
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if (ret)
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return ret;
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vol_args = memdup_user(arg, sizeof(*vol_args));
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if (IS_ERR(vol_args)) {
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ret = PTR_ERR(vol_args);
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goto err_drop;
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goto out;
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}
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if (vol_args->flags & ~BTRFS_DEVICE_REMOVE_ARGS_MASK) {
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ret = -EOPNOTSUPP;
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goto out;
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}
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vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
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if (!(vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID) &&
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strcmp("cancel", vol_args->name) == 0)
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if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID) {
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args.devid = vol_args->devid;
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} else if (!strcmp("cancel", vol_args->name)) {
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cancel = true;
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} else {
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ret = btrfs_get_dev_args_from_path(fs_info, &args, vol_args->name);
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if (ret)
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goto out;
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}
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ret = mnt_want_write_file(file);
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if (ret)
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goto out;
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ret = exclop_start_or_cancel_reloc(fs_info, BTRFS_EXCLOP_DEV_REMOVE,
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cancel);
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if (ret)
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goto out;
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/* Exclusive operation is now claimed */
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goto err_drop;
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if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID)
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ret = btrfs_rm_device(fs_info, NULL, vol_args->devid, &bdev, &mode);
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else
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ret = btrfs_rm_device(fs_info, vol_args->name, 0, &bdev, &mode);
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/* Exclusive operation is now claimed */
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ret = btrfs_rm_device(fs_info, &args, &bdev, &mode);
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btrfs_exclop_finish(fs_info);
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@ -3211,17 +3216,19 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
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btrfs_info(fs_info, "device deleted: %s",
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vol_args->name);
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}
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out:
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kfree(vol_args);
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err_drop:
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mnt_drop_write_file(file);
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if (bdev)
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blkdev_put(bdev, mode);
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out:
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btrfs_put_dev_args_from_path(&args);
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kfree(vol_args);
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return ret;
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}
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static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
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{
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BTRFS_DEV_LOOKUP_ARGS(args);
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struct inode *inode = file_inode(file);
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struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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struct btrfs_ioctl_vol_args *vol_args;
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@ -3233,32 +3240,38 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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vol_args = memdup_user(arg, sizeof(*vol_args));
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if (IS_ERR(vol_args))
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return PTR_ERR(vol_args);
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vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
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if (!strcmp("cancel", vol_args->name)) {
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cancel = true;
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} else {
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ret = btrfs_get_dev_args_from_path(fs_info, &args, vol_args->name);
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if (ret)
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goto out;
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}
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ret = mnt_want_write_file(file);
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if (ret)
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return ret;
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vol_args = memdup_user(arg, sizeof(*vol_args));
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if (IS_ERR(vol_args)) {
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ret = PTR_ERR(vol_args);
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goto out_drop_write;
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}
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vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
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cancel = (strcmp("cancel", vol_args->name) == 0);
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goto out;
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ret = exclop_start_or_cancel_reloc(fs_info, BTRFS_EXCLOP_DEV_REMOVE,
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cancel);
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if (ret == 0) {
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ret = btrfs_rm_device(fs_info, vol_args->name, 0, &bdev, &mode);
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ret = btrfs_rm_device(fs_info, &args, &bdev, &mode);
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if (!ret)
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btrfs_info(fs_info, "disk deleted %s", vol_args->name);
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btrfs_exclop_finish(fs_info);
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}
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kfree(vol_args);
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out_drop_write:
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mnt_drop_write_file(file);
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if (bdev)
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blkdev_put(bdev, mode);
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out:
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btrfs_put_dev_args_from_path(&args);
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kfree(vol_args);
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return ret;
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}
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@ -2076,8 +2076,9 @@ void btrfs_scratch_superblocks(struct btrfs_fs_info *fs_info,
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update_dev_time(bdev);
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}
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int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
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u64 devid, struct block_device **bdev, fmode_t *mode)
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int btrfs_rm_device(struct btrfs_fs_info *fs_info,
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struct btrfs_dev_lookup_args *args,
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struct block_device **bdev, fmode_t *mode)
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{
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struct btrfs_device *device;
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struct btrfs_fs_devices *cur_devices;
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@ -2096,14 +2097,12 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
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if (ret)
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goto out;
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device = btrfs_find_device_by_devspec(fs_info, devid, device_path);
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if (IS_ERR(device)) {
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if (PTR_ERR(device) == -ENOENT &&
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device_path && strcmp(device_path, "missing") == 0)
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device = btrfs_find_device(fs_info->fs_devices, args);
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if (!device) {
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if (args->missing)
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ret = BTRFS_ERROR_DEV_MISSING_NOT_FOUND;
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else
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ret = PTR_ERR(device);
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ret = -ENOENT;
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goto out;
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}
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@ -529,7 +529,7 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
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void btrfs_put_dev_args_from_path(struct btrfs_dev_lookup_args *args);
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void btrfs_free_device(struct btrfs_device *device);
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int btrfs_rm_device(struct btrfs_fs_info *fs_info,
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const char *device_path, u64 devid,
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struct btrfs_dev_lookup_args *args,
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struct block_device **bdev, fmode_t *mode);
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void __exit btrfs_cleanup_fs_uuids(void);
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int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len);
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