diff options
Diffstat (limited to 'fs/inode.c')
| -rw-r--r-- | fs/inode.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/fs/inode.c b/fs/inode.c index d9a21d122926..26cdb115ce67 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1306,6 +1306,42 @@ void wake_up_inode(struct inode *inode) wake_up_bit(&inode->i_state, __I_LOCK); } +/* + * We rarely want to lock two inodes that do not have a parent/child + * relationship (such as directory, child inode) simultaneously. The + * vast majority of file systems should be able to get along fine + * without this. Do not use these functions except as a last resort. + */ +void inode_double_lock(struct inode *inode1, struct inode *inode2) +{ + if (inode1 == NULL || inode2 == NULL || inode1 == inode2) { + if (inode1) + mutex_lock(&inode1->i_mutex); + else if (inode2) + mutex_lock(&inode2->i_mutex); + return; + } + + if (inode1 < inode2) { + mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT); + mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD); + } else { + mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT); + mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD); + } +} +EXPORT_SYMBOL(inode_double_lock); + +void inode_double_unlock(struct inode *inode1, struct inode *inode2) +{ + if (inode1) + mutex_unlock(&inode1->i_mutex); + + if (inode2 && inode2 != inode1) + mutex_unlock(&inode2->i_mutex); +} +EXPORT_SYMBOL(inode_double_unlock); + static __initdata unsigned long ihash_entries; static int __init set_ihash_entries(char *str) { |