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>
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@ -1362,6 +1362,17 @@ struct btrfs_fs_info {
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wait_queue_head_t transaction_blocked_wait;
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wait_queue_head_t transaction_blocked_wait;
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wait_queue_head_t async_submit_wait;
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wait_queue_head_t async_submit_wait;
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/*
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* Used to protect the incompat_flags, compat_flags, compat_ro_flags
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* when they are updated.
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*
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* Because we do not clear the flags for ever, so we needn't use
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* the lock on the read side.
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*
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* We also needn't use the lock when we mount the fs, because
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* there is no other task which will update the flag.
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*/
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spinlock_t super_lock;
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struct btrfs_super_block *super_copy;
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struct btrfs_super_block *super_copy;
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struct btrfs_super_block *super_for_commit;
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struct btrfs_super_block *super_for_commit;
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struct block_device *__bdev;
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struct block_device *__bdev;
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@ -3688,8 +3699,15 @@ static inline void __btrfs_set_fs_incompat(struct btrfs_fs_info *fs_info,
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disk_super = fs_info->super_copy;
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disk_super = fs_info->super_copy;
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features = btrfs_super_incompat_flags(disk_super);
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features = btrfs_super_incompat_flags(disk_super);
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if (!(features & flag)) {
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if (!(features & flag)) {
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features |= flag;
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spin_lock(&fs_info->super_lock);
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btrfs_set_super_incompat_flags(disk_super, features);
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features = btrfs_super_incompat_flags(disk_super);
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if (!(features & flag)) {
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features |= flag;
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btrfs_set_super_incompat_flags(disk_super, features);
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printk(KERN_INFO "btrfs: setting %llu feature flag\n",
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flag);
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}
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spin_unlock(&fs_info->super_lock);
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}
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}
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}
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}
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@ -2086,6 +2086,7 @@ int open_ctree(struct super_block *sb,
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spin_lock_init(&fs_info->defrag_inodes_lock);
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spin_lock_init(&fs_info->defrag_inodes_lock);
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spin_lock_init(&fs_info->free_chunk_lock);
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spin_lock_init(&fs_info->free_chunk_lock);
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spin_lock_init(&fs_info->tree_mod_seq_lock);
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spin_lock_init(&fs_info->tree_mod_seq_lock);
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spin_lock_init(&fs_info->super_lock);
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rwlock_init(&fs_info->tree_mod_log_lock);
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rwlock_init(&fs_info->tree_mod_log_lock);
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mutex_init(&fs_info->reloc_mutex);
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mutex_init(&fs_info->reloc_mutex);
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seqlock_init(&fs_info->profiles_lock);
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seqlock_init(&fs_info->profiles_lock);
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@ -2349,6 +2350,10 @@ int open_ctree(struct super_block *sb,
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goto fail_alloc;
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goto fail_alloc;
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}
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}
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/*
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* Needn't use the lock because there is no other task which will
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* update the flag.
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*/
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btrfs_set_super_incompat_flags(disk_super, features);
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btrfs_set_super_incompat_flags(disk_super, features);
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features = btrfs_super_compat_ro_flags(disk_super) &
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features = btrfs_super_compat_ro_flags(disk_super) &
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@ -3674,18 +3674,10 @@ static u32 find_raid56_stripe_len(u32 data_devices, u32 dev_stripe_target)
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static void check_raid56_incompat_flag(struct btrfs_fs_info *info, u64 type)
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static void check_raid56_incompat_flag(struct btrfs_fs_info *info, u64 type)
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{
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{
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u64 features;
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if (!(type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)))
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if (!(type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)))
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return;
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return;
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features = btrfs_super_incompat_flags(info->super_copy);
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btrfs_set_fs_incompat(info, RAID56);
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if (features & BTRFS_FEATURE_INCOMPAT_RAID56)
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return;
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features |= BTRFS_FEATURE_INCOMPAT_RAID56;
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btrfs_set_super_incompat_flags(info->super_copy, features);
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printk(KERN_INFO "btrfs: setting RAID5/6 feature flag\n");
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}
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}
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static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
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static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
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