From 2d902671ce1cd98cdc88d78c481889a1b2996101 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 30 Jun 2016 08:53:27 +0200 Subject: vfs: merge .d_select_inode() into .d_real() The two methods essentially do the same: find the real dentry/inode belonging to an overlay dentry. The difference is in the usage: vfs_open() uses ->d_select_inode() and expects the function to perform copy-up if necessary based on the open flags argument. file_dentry() uses ->d_real() passing in the overlay dentry as well as the underlying inode. vfs_rename() uses ->d_select_inode() but passes zero flags. ->d_real() with a zero inode would have worked just as well here. This patch merges the functionality of ->d_select_inode() into ->d_real() by adding an 'open_flags' argument to the latter. [Al Viro] Make the signature of d_real() match that of ->d_real() again. And constify the inode argument, while we are at it. Signed-off-by: Miklos Szeredi --- include/linux/dcache.h | 28 ++++++++-------------------- include/linux/fs.h | 7 +------ 2 files changed, 9 insertions(+), 26 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dcache.h b/include/linux/dcache.h index f53fa055021a..45b22de15ede 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -139,8 +139,7 @@ struct dentry_operations { char *(*d_dname)(struct dentry *, char *, int); struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(struct dentry *, bool); - struct inode *(*d_select_inode)(struct dentry *, unsigned); - struct dentry *(*d_real)(struct dentry *, struct inode *); + struct dentry *(*d_real)(struct dentry *, const struct inode *, unsigned int); } ____cacheline_aligned; /* @@ -206,10 +205,8 @@ struct dentry_operations { #define DCACHE_MAY_FREE 0x00800000 #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */ -#define DCACHE_OP_SELECT_INODE 0x02000000 /* Unioned entry: dcache op selects inode */ - -#define DCACHE_ENCRYPTED_WITH_KEY 0x04000000 /* dir is encrypted with a valid key */ -#define DCACHE_OP_REAL 0x08000000 +#define DCACHE_ENCRYPTED_WITH_KEY 0x02000000 /* dir is encrypted with a valid key */ +#define DCACHE_OP_REAL 0x04000000 #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */ #define DCACHE_DENTRY_CURSOR 0x20000000 @@ -557,25 +554,16 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper) return upper; } -static inline struct dentry *d_real(struct dentry *dentry) +static inline struct dentry *d_real(struct dentry *dentry, + const struct inode *inode, + unsigned int flags) { if (unlikely(dentry->d_flags & DCACHE_OP_REAL)) - return dentry->d_op->d_real(dentry, NULL); + return dentry->d_op->d_real(dentry, inode, flags); else return dentry; } -static inline struct inode *vfs_select_inode(struct dentry *dentry, - unsigned open_flags) -{ - struct inode *inode = d_inode(dentry); - - if (inode && unlikely(dentry->d_flags & DCACHE_OP_SELECT_INODE)) - inode = dentry->d_op->d_select_inode(dentry, open_flags); - - return inode; -} - /** * d_real_inode - Return the real inode * @dentry: The dentry to query @@ -585,7 +573,7 @@ static inline struct inode *vfs_select_inode(struct dentry *dentry, */ static inline struct inode *d_real_inode(struct dentry *dentry) { - return d_backing_inode(d_real(dentry)); + return d_backing_inode(d_real(dentry, NULL, 0)); } diff --git a/include/linux/fs.h b/include/linux/fs.h index dd288148a6b1..bacc0733663c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1272,12 +1272,7 @@ static inline struct inode *file_inode(const struct file *f) static inline struct dentry *file_dentry(const struct file *file) { - struct dentry *dentry = file->f_path.dentry; - - if (unlikely(dentry->d_flags & DCACHE_OP_REAL)) - return dentry->d_op->d_real(dentry, file_inode(file)); - else - return dentry; + return d_real(file->f_path.dentry, file_inode(file), 0); } static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl) -- cgit v1.2.3 From e698b8a43659f9ece192fcab215abcadac8f88d7 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 30 Jun 2016 08:53:27 +0200 Subject: vfs: document ->d_real() Add missing documentation for the d_op->d_real() method and d_real() helper. Signed-off-by: Miklos Szeredi --- Documentation/filesystems/Locking | 3 +++ Documentation/filesystems/vfs.txt | 20 ++++++++++++++++++++ include/linux/dcache.h | 14 +++++++++++++- 3 files changed, 36 insertions(+), 1 deletion(-) (limited to 'include/linux') 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) -- cgit v1.2.3