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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: Jeff Layton <jlayton@redhat.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
master
J. Bruce Fields 10 years ago
committed by Al Viro
parent
commit
375e289ea8
  1. 2
      fs/ext4/ext4.h
  2. 4
      fs/ext4/ioctl.c
  3. 40
      fs/ext4/move_extent.c
  4. 36
      fs/inode.c
  5. 3
      include/linux/fs.h

2
fs/ext4/ext4.h

@ -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);

4
fs/ext4/ioctl.c

@ -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);

40
fs/ext4/move_extent.c

@ -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;
}

36
fs/inode.c

@ -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

3
include/linux/fs.h

@ -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

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