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scoutfs: add locking of link backref traversal

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Add cluster locking around the link backref item lookups during ino
to path traversal.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2017-09-28 16:45:16 -07:00
committed by Mark Fasheh
parent 3a277bac6f
commit 0e4627ea65
1 changed files with 16 additions and 2 deletions
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18
kmod/src/dir.c
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@@ -1042,6 +1042,9 @@ int scoutfs_symlink_drop(struct super_block *sb, u64 ino,
*
* Returns 0 if we added an entry, -ENOENT if we didn't, and -errno for
* search errors.
*
* Callers are comfortable with the race inherent to incrementally
* building up a path with individual locked backref item lookups.
*/
static int add_next_linkref(struct super_block *sb, u64 ino,
u64 dir_ino, char *name, unsigned int name_len,
@@ -1049,6 +1052,7 @@ static int add_next_linkref(struct super_block *sb, u64 ino,
{
struct scoutfs_link_backref_key last_lbkey;
struct scoutfs_link_backref_entry *ent;
struct scoutfs_lock *lock = NULL;
struct scoutfs_key_buf last;
struct scoutfs_key_buf key;
int len;
@@ -1072,12 +1076,18 @@ static int add_next_linkref(struct super_block *sb, u64 ino,
init_link_backref_key(&last, &last_lbkey, ino, U64_MAX, NULL, 0);
/* next backref key is now in ent */
ret = scoutfs_item_next(sb, &key, &last, NULL, NULL);
ret = scoutfs_lock_ino(sb, DLM_LOCK_PR, 0, ino, &lock);
if (ret)
goto out;
ret = scoutfs_item_next(sb, &key, &last, NULL, lock->end);
scoutfs_unlock(sb, lock, DLM_LOCK_PR);
lock = NULL;
trace_scoutfs_dir_add_next_linkref(sb, ino, dir_ino, ret, key.key_len);
if (ret < 0)
goto out;
len = (int)key.key_len - sizeof(struct scoutfs_link_backref_key);
/* XXX corruption */
if (len < 1 || len > SCOUTFS_NAME_LEN) {
@@ -1237,6 +1247,10 @@ out:
*
* Compare this to lock_rename()'s use of d_ancestor() and what it's
* caller does with the returned ancestor.
*
* The caller only holds the global rename cluster lock.
* item_d_ancestor is going to walk backref paths and acquire and
* release locks for each target inode in the path.
*/
static int verify_ancestors(struct super_block *sb, u64 p1, u64 p2,
u64 old_ino, u64 new_ino)