diff options
author | Miao Xie <miaox@cn.fujitsu.com> | 2013-04-11 10:30:16 (GMT) |
---|---|---|
committer | Josef Bacik <jbacik@fusionio.com> | 2013-05-06 19:54:46 (GMT) |
commit | ceda08642459e31673d24d7968d864390d2ce5fa (patch) | |
tree | 57d1a9be32a9a2653011b5fedf6615731af48b7f | |
parent | f42a34b2f10c411ef45f247f3000ed03ba4e80c0 (diff) | |
download | linux-fsl-qoriq-ceda08642459e31673d24d7968d864390d2ce5fa.tar.xz |
Btrfs: use a lock to protect incompat/compat flag of the super block
The following case will make the incompat/compat flag of the super block
be recovered.
Task1 |Task2
flags = btrfs_super_incompat_flags(); |
|flags = btrfs_super_incompat_flags();
flags |= new_flag1; |
|flags |= new_flag2;
btrfs_set_super_incompat_flags(flags); |
|btrfs_set_super_incompat_flags(flags);
the new_flag1 is recovered.
In order to avoid this problem, we introduce a lock named super_lock into
the btrfs_fs_info structure. If we want to update incompat/compat flags
of the super block, we must hold it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
-rw-r--r-- | fs/btrfs/ctree.h | 22 | ||||
-rw-r--r-- | fs/btrfs/disk-io.c | 5 | ||||
-rw-r--r-- | fs/btrfs/volumes.c | 10 |
3 files changed, 26 insertions, 11 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 1a85040..c3b15f8 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1362,6 +1362,17 @@ struct btrfs_fs_info { wait_queue_head_t transaction_blocked_wait; wait_queue_head_t async_submit_wait; + /* + * Used to protect the incompat_flags, compat_flags, compat_ro_flags + * when they are updated. + * + * Because we do not clear the flags for ever, so we needn't use + * the lock on the read side. + * + * We also needn't use the lock when we mount the fs, because + * there is no other task which will update the flag. + */ + spinlock_t super_lock; struct btrfs_super_block *super_copy; struct btrfs_super_block *super_for_commit; struct block_device *__bdev; @@ -3688,8 +3699,15 @@ static inline void __btrfs_set_fs_incompat(struct btrfs_fs_info *fs_info, disk_super = fs_info->super_copy; features = btrfs_super_incompat_flags(disk_super); if (!(features & flag)) { - features |= flag; - btrfs_set_super_incompat_flags(disk_super, features); + spin_lock(&fs_info->super_lock); + features = btrfs_super_incompat_flags(disk_super); + if (!(features & flag)) { + features |= flag; + btrfs_set_super_incompat_flags(disk_super, features); + printk(KERN_INFO "btrfs: setting %llu feature flag\n", + flag); + } + spin_unlock(&fs_info->super_lock); } } diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 9f83e5b..8a7a366 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2086,6 +2086,7 @@ int open_ctree(struct super_block *sb, spin_lock_init(&fs_info->defrag_inodes_lock); spin_lock_init(&fs_info->free_chunk_lock); spin_lock_init(&fs_info->tree_mod_seq_lock); + spin_lock_init(&fs_info->super_lock); rwlock_init(&fs_info->tree_mod_log_lock); mutex_init(&fs_info->reloc_mutex); seqlock_init(&fs_info->profiles_lock); @@ -2349,6 +2350,10 @@ int open_ctree(struct super_block *sb, goto fail_alloc; } + /* + * Needn't use the lock because there is no other task which will + * update the flag. + */ btrfs_set_super_incompat_flags(disk_super, features); features = btrfs_super_compat_ro_flags(disk_super) & diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 5aa52ee..76ded9e 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3674,18 +3674,10 @@ static u32 find_raid56_stripe_len(u32 data_devices, u32 dev_stripe_target) static void check_raid56_incompat_flag(struct btrfs_fs_info *info, u64 type) { - u64 features; - if (!(type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6))) return; - features = btrfs_super_incompat_flags(info->super_copy); - if (features & BTRFS_FEATURE_INCOMPAT_RAID56) - return; - - features |= BTRFS_FEATURE_INCOMPAT_RAID56; - btrfs_set_super_incompat_flags(info->super_copy, features); - printk(KERN_INFO "btrfs: setting RAID5/6 feature flag\n"); + btrfs_set_fs_incompat(info, RAID56); } static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans, |