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>
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@@ -1202,42 +1202,6 @@ mext_check_arguments(struct inode *orig_inode,
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return 0;
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}
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/**
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* ext4_inode_double_lock - Lock i_mutex on both @inode1 and @inode2
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*
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* @inode1: the inode structure
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* @inode2: the inode structure
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*
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* Lock two inodes' i_mutex
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*/
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void
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ext4_inode_double_lock(struct inode *inode1, struct inode *inode2)
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{
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BUG_ON(inode1 == inode2);
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if (inode1 < inode2) {
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mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
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mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
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} else {
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mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
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mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
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}
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}
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/**
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* ext4_inode_double_unlock - Release i_mutex on both @inode1 and @inode2
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*
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* @inode1: the inode that is released first
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* @inode2: the inode that is released second
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*
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*/
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void
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ext4_inode_double_unlock(struct inode *inode1, struct inode *inode2)
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{
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mutex_unlock(&inode1->i_mutex);
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mutex_unlock(&inode2->i_mutex);
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}
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/**
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* ext4_move_extents - Exchange the specified range of a file
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*
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@@ -1327,7 +1291,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
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return -EINVAL;
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}
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/* Protect orig and donor inodes against a truncate */
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ext4_inode_double_lock(orig_inode, donor_inode);
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lock_two_nondirectories(orig_inode, donor_inode);
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/* Wait for all existing dio workers */
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ext4_inode_block_unlocked_dio(orig_inode);
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@@ -1535,7 +1499,7 @@ out:
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ext4_double_up_write_data_sem(orig_inode, donor_inode);
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ext4_inode_resume_unlocked_dio(orig_inode);
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ext4_inode_resume_unlocked_dio(donor_inode);
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ext4_inode_double_unlock(orig_inode, donor_inode);
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unlock_two_nondirectories(orig_inode, donor_inode);
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return ret;
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}
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