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Commit 375e289e authored by J. Bruce Fields's avatar J. Bruce Fields Committed by Al Viro
Browse files

vfs: pull ext4's double-i_mutex-locking into common code 



We want to do this elsewhere as well.

Also catch any attempts to use it for directories (where this ordering
would conflict with ancestor-first directory ordering in lock_rename).

Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Dave Chinner <david@fromorbit.com>
Acked-by: default avatarJeff Layton <jlayton@redhat.com>
Acked-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent f27c9298

fs/ext4/ext4.h

+0 −2
Original line number Diff line number Diff line
@@ -2734,8 +2734,6 @@ extern void ext4_double_down_write_data_sem(struct inode *first, 
					    struct inode *second);

extern void ext4_double_up_write_data_sem(struct inode *orig_inode,

					  struct inode *donor_inode);

void ext4_inode_double_lock(struct inode *inode1, struct inode *inode2);

void ext4_inode_double_unlock(struct inode *inode1, struct inode *inode2);

extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,

			     __u64 start_orig, __u64 start_donor,

			     __u64 len, __u64 *moved_len);

fs/ext4/ioctl.c

+2 −2
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ static long swap_inode_boot_loader(struct super_block *sb, 


	/* Protect orig inodes against a truncate and make sure,

	 * that only 1 swap_inode_boot_loader is running. */

	ext4_inode_double_lock(inode, inode_bl);

	lock_two_nondirectories(inode, inode_bl);



	truncate_inode_pages(&inode->i_data, 0);

	truncate_inode_pages(&inode_bl->i_data, 0);
@@ -205,7 +205,7 @@ static long swap_inode_boot_loader(struct super_block *sb, 
	ext4_inode_resume_unlocked_dio(inode);

	ext4_inode_resume_unlocked_dio(inode_bl);



	ext4_inode_double_unlock(inode, inode_bl);

	unlock_two_nondirectories(inode, inode_bl);



	iput(inode_bl);

fs/ext4/move_extent.c

+2 −38
Original line number Diff line number Diff line
@@ -1202,42 +1202,6 @@ mext_check_arguments(struct inode *orig_inode, 
	return 0;

}



/**

 * ext4_inode_double_lock - Lock i_mutex on both @inode1 and @inode2

 *

 * @inode1:	the inode structure

 * @inode2:	the inode structure

 *

 * Lock two inodes' i_mutex

 */

void

ext4_inode_double_lock(struct inode *inode1, struct inode *inode2)

{

	BUG_ON(inode1 == inode2);

	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);

	}

}



/**

 * ext4_inode_double_unlock - Release i_mutex on both @inode1 and @inode2

 *

 * @inode1:     the inode that is released first

 * @inode2:     the inode that is released second

 *

 */



void

ext4_inode_double_unlock(struct inode *inode1, struct inode *inode2)

{

	mutex_unlock(&inode1->i_mutex);

	mutex_unlock(&inode2->i_mutex);

}



/**

 * ext4_move_extents - Exchange the specified range of a file

 *
@@ -1327,7 +1291,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
		return -EINVAL;

	}

	/* Protect orig and donor inodes against a truncate */

	ext4_inode_double_lock(orig_inode, donor_inode);

	lock_two_nondirectories(orig_inode, donor_inode);



	/* Wait for all existing dio workers */

	ext4_inode_block_unlocked_dio(orig_inode);
@@ -1535,7 +1499,7 @@ out: 
	ext4_double_up_write_data_sem(orig_inode, donor_inode);

	ext4_inode_resume_unlocked_dio(orig_inode);

	ext4_inode_resume_unlocked_dio(donor_inode);

	ext4_inode_double_unlock(orig_inode, donor_inode);

	unlock_two_nondirectories(orig_inode, donor_inode);



	return ret;

}

fs/inode.c

+36 −0
Original line number Diff line number Diff line
@@ -942,6 +942,42 @@ void unlock_new_inode(struct inode *inode) 
}

EXPORT_SYMBOL(unlock_new_inode);



/**

 * lock_two_nondirectories - take two i_mutexes on non-directory objects

 * @inode1: first inode to lock

 * @inode2: second inode to lock

 */

void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)

{

	WARN_ON_ONCE(S_ISDIR(inode1->i_mode));

	if (inode1 == inode2 || !inode2) {

		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);

		return;

	}

	WARN_ON_ONCE(S_ISDIR(inode2->i_mode));

	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(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)

{

	mutex_unlock(&inode1->i_mutex);

	if (inode2 && 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

include/linux/fs.h

+3 −0
Original line number Diff line number Diff line
@@ -637,6 +637,9 @@ enum inode_i_mutex_lock_class 
	I_MUTEX_QUOTA

};



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