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Btrfs: use seqlock to protect fs_info->avail_{data, metadata, system}…
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…_alloc_bits

There is no lock to protect
  fs_info->avail_{data, metadata, system}_alloc_bits,
it may introduce some problem, such as the wrong profile
information, so we add a seqlock to protect them.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
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Miao Xie authored and Josef Bacik committed Feb 20, 2013
1 parent df0af1a commit de98ced
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Showing 4 changed files with 49 additions and 32 deletions.
2 changes: 2 additions & 0 deletions fs/btrfs/ctree.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1483,6 +1483,8 @@ struct btrfs_fs_info {
struct rb_root defrag_inodes;
atomic_t defrag_running;

/* Used to protect avail_{data, metadata, system}_alloc_bits */
seqlock_t profiles_lock;
/*
* these three are in extended format (availability of single
* chunks is denoted by BTRFS_AVAIL_ALLOC_BIT_SINGLE bit, other
Expand Down
1 change: 1 addition & 0 deletions fs/btrfs/disk-io.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2040,6 +2040,7 @@ int open_ctree(struct super_block *sb,
spin_lock_init(&fs_info->tree_mod_seq_lock);
rwlock_init(&fs_info->tree_mod_log_lock);
mutex_init(&fs_info->reloc_mutex);
seqlock_init(&fs_info->profiles_lock);

init_completion(&fs_info->kobj_unregister);
INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
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22 changes: 16 additions & 6 deletions fs/btrfs/extent-tree.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3227,12 +3227,14 @@ static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
u64 extra_flags = chunk_to_extended(flags) &
BTRFS_EXTENDED_PROFILE_MASK;

write_seqlock(&fs_info->profiles_lock);
if (flags & BTRFS_BLOCK_GROUP_DATA)
fs_info->avail_data_alloc_bits |= extra_flags;
if (flags & BTRFS_BLOCK_GROUP_METADATA)
fs_info->avail_metadata_alloc_bits |= extra_flags;
if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
fs_info->avail_system_alloc_bits |= extra_flags;
write_sequnlock(&fs_info->profiles_lock);
}

/*
Expand Down Expand Up @@ -3324,12 +3326,18 @@ u64 btrfs_reduce_alloc_profile(struct btrfs_root *root, u64 flags)

static u64 get_alloc_profile(struct btrfs_root *root, u64 flags)
{
if (flags & BTRFS_BLOCK_GROUP_DATA)
flags |= root->fs_info->avail_data_alloc_bits;
else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
flags |= root->fs_info->avail_system_alloc_bits;
else if (flags & BTRFS_BLOCK_GROUP_METADATA)
flags |= root->fs_info->avail_metadata_alloc_bits;
unsigned seq;

do {
seq = read_seqbegin(&root->fs_info->profiles_lock);

if (flags & BTRFS_BLOCK_GROUP_DATA)
flags |= root->fs_info->avail_data_alloc_bits;
else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
flags |= root->fs_info->avail_system_alloc_bits;
else if (flags & BTRFS_BLOCK_GROUP_METADATA)
flags |= root->fs_info->avail_metadata_alloc_bits;
} while (read_seqretry(&root->fs_info->profiles_lock, seq));

return btrfs_reduce_alloc_profile(root, flags);
}
Expand Down Expand Up @@ -7967,12 +7975,14 @@ static void clear_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
u64 extra_flags = chunk_to_extended(flags) &
BTRFS_EXTENDED_PROFILE_MASK;

write_seqlock(&fs_info->profiles_lock);
if (flags & BTRFS_BLOCK_GROUP_DATA)
fs_info->avail_data_alloc_bits &= ~extra_flags;
if (flags & BTRFS_BLOCK_GROUP_METADATA)
fs_info->avail_metadata_alloc_bits &= ~extra_flags;
if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
fs_info->avail_system_alloc_bits &= ~extra_flags;
write_sequnlock(&fs_info->profiles_lock);
}

int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
Expand Down
56 changes: 30 additions & 26 deletions fs/btrfs/volumes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1430,14 +1430,19 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
u64 devid;
u64 num_devices;
u8 *dev_uuid;
unsigned seq;
int ret = 0;
bool clear_super = false;

mutex_lock(&uuid_mutex);

all_avail = root->fs_info->avail_data_alloc_bits |
root->fs_info->avail_system_alloc_bits |
root->fs_info->avail_metadata_alloc_bits;
do {
seq = read_seqbegin(&root->fs_info->profiles_lock);

all_avail = root->fs_info->avail_data_alloc_bits |
root->fs_info->avail_system_alloc_bits |
root->fs_info->avail_metadata_alloc_bits;
} while (read_seqretry(&root->fs_info->profiles_lock, seq));

num_devices = root->fs_info->fs_devices->num_devices;
btrfs_dev_replace_lock(&root->fs_info->dev_replace);
Expand Down Expand Up @@ -3043,6 +3048,7 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
int mixed = 0;
int ret;
u64 num_devices;
unsigned seq;

if (btrfs_fs_closing(fs_info) ||
atomic_read(&fs_info->balance_pause_req) ||
Expand Down Expand Up @@ -3126,22 +3132,26 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
/* allow to reduce meta or sys integrity only if force set */
allowed = BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
BTRFS_BLOCK_GROUP_RAID10;
if (((bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
(fs_info->avail_system_alloc_bits & allowed) &&
!(bctl->sys.target & allowed)) ||
((bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
(fs_info->avail_metadata_alloc_bits & allowed) &&
!(bctl->meta.target & allowed))) {
if (bctl->flags & BTRFS_BALANCE_FORCE) {
printk(KERN_INFO "btrfs: force reducing metadata "
"integrity\n");
} else {
printk(KERN_ERR "btrfs: balance will reduce metadata "
"integrity, use force if you want this\n");
ret = -EINVAL;
goto out;
do {
seq = read_seqbegin(&fs_info->profiles_lock);

if (((bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
(fs_info->avail_system_alloc_bits & allowed) &&
!(bctl->sys.target & allowed)) ||
((bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
(fs_info->avail_metadata_alloc_bits & allowed) &&
!(bctl->meta.target & allowed))) {
if (bctl->flags & BTRFS_BALANCE_FORCE) {
printk(KERN_INFO "btrfs: force reducing metadata "
"integrity\n");
} else {
printk(KERN_ERR "btrfs: balance will reduce metadata "
"integrity, use force if you want this\n");
ret = -EINVAL;
goto out;
}
}
}
} while (read_seqretry(&fs_info->profiles_lock, seq));

if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) {
int num_tolerated_disk_barrier_failures;
Expand Down Expand Up @@ -3980,21 +3990,15 @@ static noinline int init_first_rw_device(struct btrfs_trans_handle *trans,
if (ret)
return ret;

alloc_profile = BTRFS_BLOCK_GROUP_METADATA |
fs_info->avail_metadata_alloc_bits;
alloc_profile = btrfs_reduce_alloc_profile(root, alloc_profile);

alloc_profile = btrfs_get_alloc_profile(extent_root, 0);
ret = __btrfs_alloc_chunk(trans, extent_root, &map, &chunk_size,
&stripe_size, chunk_offset, alloc_profile);
if (ret)
return ret;

sys_chunk_offset = chunk_offset + chunk_size;

alloc_profile = BTRFS_BLOCK_GROUP_SYSTEM |
fs_info->avail_system_alloc_bits;
alloc_profile = btrfs_reduce_alloc_profile(root, alloc_profile);

alloc_profile = btrfs_get_alloc_profile(fs_info->chunk_root, 0);
ret = __btrfs_alloc_chunk(trans, extent_root, &sys_map,
&sys_chunk_size, &sys_stripe_size,
sys_chunk_offset, alloc_profile);
Expand Down

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