diff options
| -rw-r--r-- | Documentation/filesystems/Locking | 3 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 20 | ||||
| -rw-r--r-- | include/linux/dcache.h | 14 |
3 files changed, 36 insertions, 1 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 75eea7ce3d7c..898d3cecd8a6 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -20,6 +20,8 @@ prototypes: char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen); struct vfsmount *(*d_automount)(struct path *path); int (*d_manage)(struct dentry *, bool); + struct dentry *(*d_real)(struct dentry *, const struct inode *, + unsigned int); locking rules: rename_lock ->d_lock may block rcu-walk @@ -34,6 +36,7 @@ d_iput: no no yes no d_dname: no no no no d_automount: no no yes no d_manage: no no yes (ref-walk) maybe +d_real no no yes no --------------------------- inode_operations --------------------------- prototypes: diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index c61a223ef3ff..1c934dd2c47d 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -938,6 +938,8 @@ struct dentry_operations { char *(*d_dname)(struct dentry *, char *, int); struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(struct dentry *, bool); + struct dentry *(*d_real)(struct dentry *, const struct inode *, + unsigned int); }; d_revalidate: called when the VFS needs to revalidate a dentry. This @@ -1060,6 +1062,24 @@ struct dentry_operations { This function is only used if DCACHE_MANAGE_TRANSIT is set on the dentry being transited from. + d_real: overlay/union type filesystems implement this method to return one of + the underlying dentries hidden by the overlay. It is used in three + different modes: + + Called from open it may need to copy-up the file depending on the + supplied open flags. This mode is selected with a non-zero flags + argument. In this mode the d_real method can return an error. + + Called from file_dentry() it returns the real dentry matching the inode + argument. The real dentry may be from a lower layer already copied up, + but still referenced from the file. This mode is selected with a + non-NULL inode argument. This will always succeed. + + With NULL inode and zero flags the topmost real underlying dentry is + returned. This will always succeed. + + This method is never called with both non-NULL inode and non-zero flags. + Example : static char *pipefs_dname(struct dentry *dent, char *buffer, int buflen) diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 45b22de15ede..14df83609c7f 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -139,7 +139,8 @@ struct dentry_operations { char *(*d_dname)(struct dentry *, char *, int); struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(struct dentry *, bool); - struct dentry *(*d_real)(struct dentry *, const struct inode *, unsigned int); + struct dentry *(*d_real)(struct dentry *, const struct inode *, + unsigned int); } ____cacheline_aligned; /* @@ -554,6 +555,17 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper) return upper; } +/** + * d_real - Return the real dentry + * @dentry: the dentry to query + * @inode: inode to select the dentry from multiple layers (can be NULL) + * @flags: open flags to control copy-up behavior + * + * If dentry is on an union/overlay, then return the underlying, real dentry. + * Otherwise return the dentry itself. + * + * See also: Documentation/filesystems/vfs.txt + */ static inline struct dentry *d_real(struct dentry *dentry, const struct inode *inode, unsigned int flags) |