From: David Sterba dsterba@suse.com
[ Upstream commit 0e94c4f45d14cf89d1f40c91b0a8517e791672a7 ]
The scrub context is allocated with GFP_KERNEL and called from btrfs_scrub_dev under the fs_info::device_list_mutex. This is not safe regarding reclaim that could try to flush filesystem data in order to get the memory. And the device_list_mutex is held during superblock commit, so this would cause a lockup.
Move the alocation and initialization before any changes that require the mutex.
Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/scrub.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index efaad3e1b295a..56c4d2236484f 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3837,13 +3837,18 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, return -EINVAL; }
+ /* Allocate outside of device_list_mutex */ + sctx = scrub_setup_ctx(fs_info, is_dev_replace); + if (IS_ERR(sctx)) + return PTR_ERR(sctx);
mutex_lock(&fs_info->fs_devices->device_list_mutex); dev = btrfs_find_device(fs_info, devid, NULL, NULL); if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) && !is_dev_replace)) { mutex_unlock(&fs_info->fs_devices->device_list_mutex); - return -ENODEV; + ret = -ENODEV; + goto out_free_ctx; }
if (!is_dev_replace && !readonly && @@ -3851,7 +3856,8 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, mutex_unlock(&fs_info->fs_devices->device_list_mutex); btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable", rcu_str_deref(dev->name)); - return -EROFS; + ret = -EROFS; + goto out_free_ctx; }
mutex_lock(&fs_info->scrub_lock); @@ -3859,7 +3865,8 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) { mutex_unlock(&fs_info->scrub_lock); mutex_unlock(&fs_info->fs_devices->device_list_mutex); - return -EIO; + ret = -EIO; + goto out_free_ctx; }
btrfs_dev_replace_read_lock(&fs_info->dev_replace); @@ -3869,7 +3876,8 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, btrfs_dev_replace_read_unlock(&fs_info->dev_replace); mutex_unlock(&fs_info->scrub_lock); mutex_unlock(&fs_info->fs_devices->device_list_mutex); - return -EINPROGRESS; + ret = -EINPROGRESS; + goto out_free_ctx; } btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
@@ -3877,16 +3885,9 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, if (ret) { mutex_unlock(&fs_info->scrub_lock); mutex_unlock(&fs_info->fs_devices->device_list_mutex); - return ret; + goto out_free_ctx; }
- sctx = scrub_setup_ctx(fs_info, is_dev_replace); - if (IS_ERR(sctx)) { - mutex_unlock(&fs_info->scrub_lock); - mutex_unlock(&fs_info->fs_devices->device_list_mutex); - scrub_workers_put(fs_info); - return PTR_ERR(sctx); - } sctx->readonly = readonly; dev->scrub_ctx = sctx; mutex_unlock(&fs_info->fs_devices->device_list_mutex); @@ -3939,6 +3940,11 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
scrub_put_ctx(sctx);
+ return ret; + +out_free_ctx: + scrub_free_ctx(sctx); + return ret; }