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 diff --git a/fs/dcache.c b/fs/dcache.c index d6847d7..5405b89 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1729,7 +1729,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | DCACHE_OP_DELETE | - DCACHE_OP_SELECT_INODE | DCACHE_OP_REAL)); dentry->d_op = op; if (!op) @@ -1746,8 +1745,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) dentry->d_flags |= DCACHE_OP_DELETE; if (op->d_prune) dentry->d_flags |= DCACHE_OP_PRUNE; - if (op->d_select_inode) - dentry->d_flags |= DCACHE_OP_SELECT_INODE; if (op->d_real) dentry->d_flags |= DCACHE_OP_REAL; diff --git a/fs/namei.c b/fs/namei.c index 70580ab..bb7a2e0 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -4328,7 +4328,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, * Check source == target. * On overlayfs need to look at underlying inodes. */ - if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0)) + if (d_real_inode(old_dentry) == d_real_inode(new_dentry)) return 0; error = may_delete(old_dir, old_dentry, is_dir); diff --git a/fs/open.c b/fs/open.c index 93ae3cd..bf66cf1 100644 --- a/fs/open.c +++ b/fs/open.c @@ -840,13 +840,13 @@ EXPORT_SYMBOL(file_path); int vfs_open(const struct path *path, struct file *file, const struct cred *cred) { - struct inode *inode = vfs_select_inode(path->dentry, file->f_flags); + struct dentry *dentry = d_real(path->dentry, NULL, file->f_flags); - if (IS_ERR(inode)) - return PTR_ERR(inode); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); file->f_path = *path; - return do_dentry_open(file, inode, NULL, cred); + return do_dentry_open(file, d_backing_inode(dentry), NULL, cred); } struct file *dentry_open(const struct path *path, int flags, diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 1dbeab6..e08cd94 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -325,36 +325,25 @@ static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, return true; } -struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags) +int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) { - int err; + int err = 0; struct path realpath; enum ovl_path_type type; - if (d_is_dir(dentry)) - return d_backing_inode(dentry); - type = ovl_path_real(dentry, &realpath); if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { err = ovl_want_write(dentry); - if (err) - return ERR_PTR(err); - - if (file_flags & O_TRUNC) - err = ovl_copy_up_truncate(dentry); - else - err = ovl_copy_up(dentry); - ovl_drop_write(dentry); - if (err) - return ERR_PTR(err); - - ovl_path_upper(dentry, &realpath); + if (!err) { + if (file_flags & O_TRUNC) + err = ovl_copy_up_truncate(dentry); + else + err = ovl_copy_up(dentry); + ovl_drop_write(dentry); + } } - if (realpath.dentry->d_flags & DCACHE_OP_SELECT_INODE) - return realpath.dentry->d_op->d_select_inode(realpath.dentry, file_flags); - - return d_backing_inode(realpath.dentry); + return err; } static const struct inode_operations ovl_file_inode_operations = { diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 4bd9b5b..6b9fd25 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -179,7 +179,7 @@ ssize_t ovl_getxattr(struct dentry *dentry, struct inode *inode, const char *name, void *value, size_t size); ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size); int ovl_removexattr(struct dentry *dentry, const char *name); -struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags); +int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags); struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, struct ovl_entry *oe); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index ce02f46..035c176 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -304,7 +304,9 @@ static void ovl_dentry_release(struct dentry *dentry) } } -static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode) +static struct dentry *ovl_d_real(struct dentry *dentry, + const struct inode *inode, + unsigned int open_flags) { struct dentry *real; @@ -314,6 +316,16 @@ static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode) goto bug; } + if (d_is_negative(dentry)) + return dentry; + + if (open_flags) { + int err = ovl_open_maybe_copy_up(dentry, open_flags); + + if (err) + return ERR_PTR(err); + } + real = ovl_dentry_upper(dentry); if (real && (!inode || inode == d_inode(real))) return real; @@ -326,9 +338,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode) return real; /* Handle recursion */ - if (real->d_flags & DCACHE_OP_REAL) - return real->d_op->d_real(real, inode); - + return d_real(real, inode, open_flags); bug: WARN(1, "ovl_d_real(%pd4, %s:%lu\n): real dentry not found\n", dentry, inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); @@ -378,13 +388,11 @@ static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) static const struct dentry_operations ovl_dentry_operations = { .d_release = ovl_dentry_release, - .d_select_inode = ovl_d_select_inode, .d_real = ovl_d_real, }; static const struct dentry_operations ovl_reval_dentry_operations = { .d_release = ovl_dentry_release, - .d_select_inode = ovl_d_select_inode, .d_real = ovl_d_real, .d_revalidate = ovl_dentry_revalidate, .d_weak_revalidate = ovl_dentry_weak_revalidate, diff --git a/include/linux/dcache.h b/include/linux/dcache.h index f53fa05..45b22de 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 dd28814..bacc073 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 v0.10.2 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 diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 75eea7c..898d3ce 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 c61a223..1c934dd 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 45b22de..14df836 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 v0.10.2 From 0cac643c102c0632dc2cc81e2490b0fec1cac0af Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 30 Jun 2016 08:53:28 +0200 Subject: vfs: clean up documentation Signed-off-by: Miklos Szeredi diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 898d3ce..d4def7b 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -69,7 +69,6 @@ prototypes: struct file *, unsigned open_flag, umode_t create_mode, int *opened); int (*tmpfile) (struct inode *, struct dentry *, umode_t); - int (*dentry_open)(struct dentry *, struct file *, const struct cred *); locking rules: all may block @@ -98,7 +97,6 @@ fiemap: no update_time: no atomic_open: yes tmpfile: no -dentry_open: no Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on victim. diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index 1c934dd..01c4f17 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -364,7 +364,6 @@ struct inode_operations { int (*atomic_open)(struct inode *, struct dentry *, struct file *, unsigned open_flag, umode_t create_mode, int *opened); int (*tmpfile) (struct inode *, struct dentry *, umode_t); - int (*dentry_open)(struct dentry *, struct file *, const struct cred *); }; Again, all methods are called without any locks being held, unless @@ -696,13 +695,6 @@ struct address_space_operations { but instead uses bmap to find out where the blocks in the file are and uses those addresses directly. - dentry_open: *WARNING: probably going away soon, do not use!* This is an - alternative to f_op->open(), the difference is that this method may open - a file not necessarily originating from the same filesystem as the one - i_op->open() was called on. It may be useful for stacking filesystems - which want to allow native I/O directly on underlying files. - - invalidatepage: If a page has PagePrivate set, then invalidatepage will be called when part or all of the page is to be removed from the address space. This generally corresponds to either a @@ -1024,6 +1016,14 @@ struct dentry_operations { at the end of the buffer, and returns a pointer to the first char. dynamic_dname() helper function is provided to take care of this. + Example : + + static char *pipefs_dname(struct dentry *dent, char *buffer, int buflen) + { + return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]", + dentry->d_inode->i_ino); + } + d_automount: called when an automount dentry is to be traversed (optional). This should create a new VFS mount record and return the record to the caller. The caller is supplied with a path parameter giving the @@ -1080,14 +1080,6 @@ struct dentry_operations { 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) -{ - return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]", - dentry->d_inode->i_ino); -} - Each dentry has a pointer to its parent dentry, as well as a hash list of child dentries. Child dentries are basically like files in a directory. -- cgit v0.10.2