diff mbox series

[v7,4/5] btrfs: Reset device size when btrfs_update_device() failed in btrfs_grow_device()

Message ID 20200211051153.19466-5-wqu@suse.com (mailing list archive)
State New, archived
Headers show
Series Introduce per-profile available space array to avoid over-confident can_overcommit() | expand

Commit Message

Qu Wenruo Feb. 11, 2020, 5:11 a.m. UTC
When btrfs_update_device() failed due to ENOMEM, we didn't reset device
size back to its original size, causing the in-memory device size larger
than original.

If somehow the memory pressure get solved, and the fs committed, since
the device item is not updated, but super block total size get updated,
it would cause mount failure due to size mismatch.

So here revert device size and super size to its original size when
btrfs_update_device() failed, just like what we did in shrink_device().

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/volumes.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1886fa20530d..4750255d02a8 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2846,6 +2846,7 @@  int btrfs_grow_device(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_fs_info *fs_info = device->fs_info;
 	struct btrfs_super_block *super_copy = fs_info->super_copy;
+	u64 old_device_size;
 	u64 old_total;
 	u64 diff;
 	int ret;
@@ -2856,6 +2857,7 @@  int btrfs_grow_device(struct btrfs_trans_handle *trans,
 	new_size = round_down(new_size, fs_info->sectorsize);
 
 	mutex_lock(&fs_info->chunk_mutex);
+	old_device_size = device->total_bytes;
 	old_total = btrfs_super_total_bytes(super_copy);
 	diff = round_down(new_size - device->total_bytes, fs_info->sectorsize);
 
@@ -2878,9 +2880,25 @@  int btrfs_grow_device(struct btrfs_trans_handle *trans,
 	ret = calc_per_profile_avail(fs_info);
 	mutex_unlock(&fs_info->chunk_mutex);
 	if (ret < 0)
-		return ret;
+		goto out;
 
-	return btrfs_update_device(trans, device);
+	ret = btrfs_update_device(trans, device);
+out:
+	if (ret < 0) {
+		/*
+		 * Although we dropped chunk_mutex halfway for
+		 * btrfs_update_device(), we have FS_EXCL_OP bit to prevent
+		 * shrinking/growing race.
+		 * So we're safe to use the old size directly.
+		 */
+		mutex_lock(&fs_info->chunk_mutex);
+		btrfs_set_super_total_bytes(super_copy, old_total);
+		device->fs_devices->total_rw_bytes -= diff;
+		btrfs_device_set_total_bytes(device, old_device_size);
+		btrfs_device_set_disk_total_bytes(device, old_device_size);
+		mutex_unlock(&fs_info->chunk_mutex);
+	}
+	return ret;
 }
 
 static int btrfs_free_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)