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Commit c46c8877 authored by Jeff Layton's avatar Jeff Layton Committed by Al Viro
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vfs: document locking requirements for d_move, __d_move and d_materialise_unique 



Adding a comment to d_materialise_unique per Al's request...

d_move and __d_move have some pretty substantial locking requirements,
but they are not clearly documented. Add some comments spelling them
out. Also, document the requirement for the i_mutex of the parent in
d_materialise_unique.

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 41c96486

fs/dcache.c

+7 −4
Original line number Diff line number Diff line
@@ -2138,8 +2138,9 @@ static void dentry_unlock_parents_for_move(struct dentry *dentry, 
 * @target: new dentry

 *

 * Update the dcache to reflect the move of a file name. Negative

 * dcache entries should not be moved in this way.  Caller hold

 * rename_lock.

 * dcache entries should not be moved in this way. Caller must hold

 * rename_lock, the i_mutex of the source and target directories,

 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().

 */

static void __d_move(struct dentry * dentry, struct dentry * target)

{
@@ -2202,7 +2203,8 @@ static void __d_move(struct dentry * dentry, struct dentry * target) 
 * @target: new dentry

 *

 * Update the dcache to reflect the move of a file name. Negative

 * dcache entries should not be moved in this way.

 * dcache entries should not be moved in this way. See the locking

 * requirements for __d_move.

 */

void d_move(struct dentry *dentry, struct dentry *target)

{
@@ -2320,7 +2322,8 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) 
 * @inode: inode to bind to the dentry, to which aliases may be attached

 *

 * Introduces an dentry into the tree, substituting an extant disconnected

 * root directory alias in its place if there is one

 * root directory alias in its place if there is one. Caller must hold the

 * i_mutex of the parent directory.

 */

struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)

{