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fs: add {lock,unlock}_two_nondirectories for 3.18 backport 

Change-Id: Iea7a9d8b87442764bb2fd16306996b494e6ed1b3
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Theodore Ts'o <tytso@google.com>
Git-commit: b226d199c38e353cf59240000704a4cfdd40a954
Git-repo: https://android.googlesource.com/kernel/common.git
Signed-off-by: Kaushal Kumar <kaushalk@codeaurora.org>
This commit is contained in:
Theodore Ts'o 2015-01-22 12:06:09 -05:00 committed by Kaushal Kumar
parent d2e323cd8b
commit 805074fa98
2 changed files with 41 additions and 1 deletions
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35
fs/inode.c
View File

@ -979,6 +979,41 @@ void unlock_new_inode(struct inode *inode)
}
EXPORT_SYMBOL(unlock_new_inode);
/**
* lock_two_nondirectories - take two i_mutexes on non-directory objects
*
* Lock any non-NULL argument that is not a directory.
* Zero, one or two objects may be locked by this function.
*
* @inode1: first inode to lock
* @inode2: second inode to lock
*/
void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
{
if (inode1 > inode2)
swap(inode1, inode2);
if (inode1 && !S_ISDIR(inode1->i_mode))
mutex_lock(&inode1->i_mutex);
if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
mutex_lock_nested(&inode2->i_mutex, I_MUTEX_NONDIR2);
}
EXPORT_SYMBOL(lock_two_nondirectories);
/**
* unlock_two_nondirectories - release locks from lock_two_nondirectories()
* @inode1: first inode to unlock
* @inode2: second inode to unlock
*/
void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
{
if (inode1 && !S_ISDIR(inode1->i_mode))
mutex_unlock(&inode1->i_mutex);
if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
mutex_unlock(&inode2->i_mutex);
}
EXPORT_SYMBOL(unlock_two_nondirectories);
/**
* iget5_locked - obtain an inode from a mounted file system
* @sb: super block of file system

7
include/linux/fs.h
View File

@ -632,9 +632,14 @@ enum inode_i_mutex_lock_class
I_MUTEX_PARENT,
I_MUTEX_CHILD,
I_MUTEX_XATTR,
I_MUTEX_QUOTA
I_MUTEX_QUOTA,
I_MUTEX_NONDIR2,
I_MUTEX_PARENT2,
};
void lock_two_nondirectories(struct inode *, struct inode*);
void unlock_two_nondirectories(struct inode *, struct inode*);
/*
* NOTE: in a 32bit arch with a preemptable kernel and
* an UP compile the i_size_read/write must be atomic