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| author | Chris Mason <chris.mason@oracle.com> | 2009-06-10 15:17:02 -0400 |
|---|---|---|
| committer | Chris Mason <chris.mason@oracle.com> | 2009-06-10 15:17:02 -0400 |
| commit | e5e9a5206a171b2c467e494aebcdcf70c47289bc (patch) | |
| tree | d9a6a89cccbd084db923f1661b52d5a1dfdb83fe /fs/btrfs/disk-io.c | |
| parent | 7df336ec1266dccbb253bac52c529d3dcc7c22d0 (diff) | |
| download | linux-e5e9a5206a171b2c467e494aebcdcf70c47289bc.tar.bz2 | |
Btrfs: avoid races between super writeout and device list updates
On multi-device filesystems, btrfs writes supers to all of the devices
before considering a sync complete. There wasn't any additional
locking between super writeout and the device list management code
because device management was done inside a transaction and
super writeout only happened with no transation writers running.
With the btrfs fsync log and other async transaction updates, this
has been racey for some time. This adds a mutex to protect
the device list. The existing volume mutex could not be reused due to
transaction lock ordering requirements.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/disk-io.c')
| -rw-r--r-- | fs/btrfs/disk-io.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 6c54c210dfd0..b7ddc77fa568 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2111,7 +2111,7 @@ static int write_dev_supers(struct btrfs_device *device, int write_all_supers(struct btrfs_root *root, int max_mirrors) { - struct list_head *head = &root->fs_info->fs_devices->devices; + struct list_head *head; struct btrfs_device *dev; struct btrfs_super_block *sb; struct btrfs_dev_item *dev_item; @@ -2126,6 +2126,9 @@ int write_all_supers(struct btrfs_root *root, int max_mirrors) sb = &root->fs_info->super_for_commit; dev_item = &sb->dev_item; + + mutex_lock(&root->fs_info->fs_devices->device_list_mutex); + head = &root->fs_info->fs_devices->devices; list_for_each_entry(dev, head, dev_list) { if (!dev->bdev) { total_errors++; @@ -2169,6 +2172,7 @@ int write_all_supers(struct btrfs_root *root, int max_mirrors) if (ret) total_errors++; } + mutex_unlock(&root->fs_info->fs_devices->device_list_mutex); if (total_errors > max_errors) { printk(KERN_ERR "btrfs: %d errors while writing supers\n", total_errors); |