From b18825a7c8e37a7cf6abb97a12a6ad71af160de7 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 12 Sep 2013 19:22:53 +0100 Subject: [PATCH] VFS: Put a small type field into struct dentry::d_flags Put a type field into struct dentry::d_flags to indicate if the dentry is one of the following types that relate particularly to pathwalk: Miss (negative dentry) Directory "Automount" directory (defective - no i_op->lookup()) Symlink Other (regular, socket, fifo, device) The type field is set to one of the first five types on a dentry by calls to __d_instantiate() and d_obtain_alias() from information in the inode (if one is given). The type is cleared by dentry_unlink_inode() when it reconstitutes an existing dentry as a negative dentry. Accessors provided are: d_set_type(dentry, type) d_is_directory(dentry) d_is_autodir(dentry) d_is_symlink(dentry) d_is_file(dentry) d_is_negative(dentry) d_is_positive(dentry) A bunch of checks in pathname resolution switched to those. Signed-off-by: David Howells Signed-off-by: Al Viro --- fs/dcache.c | 42 +++++++++++++++-- fs/namei.c | 95 +++++++++++++++---------------------- include/linux/dcache.h | 103 +++++++++++++++++++++++++++++++++-------- 3 files changed, 158 insertions(+), 82 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index fb7bcf3ba5d6..525770e576db 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -343,6 +343,7 @@ static void dentry_unlink_inode(struct dentry * dentry) __releases(dentry->d_inode->i_lock) { struct inode *inode = dentry->d_inode; + __d_clear_type(dentry); dentry->d_inode = NULL; hlist_del_init(&dentry->d_alias); dentry_rcuwalk_barrier(dentry); @@ -1648,14 +1649,42 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) } EXPORT_SYMBOL(d_set_d_op); +static unsigned d_flags_for_inode(struct inode *inode) +{ + unsigned add_flags = DCACHE_FILE_TYPE; + + if (!inode) + return DCACHE_MISS_TYPE; + + if (S_ISDIR(inode->i_mode)) { + add_flags = DCACHE_DIRECTORY_TYPE; + if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) { + if (unlikely(!inode->i_op->lookup)) + add_flags = DCACHE_AUTODIR_TYPE; + else + inode->i_opflags |= IOP_LOOKUP; + } + } else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { + if (unlikely(inode->i_op->follow_link)) + add_flags = DCACHE_SYMLINK_TYPE; + else + inode->i_opflags |= IOP_NOFOLLOW; + } + + if (unlikely(IS_AUTOMOUNT(inode))) + add_flags |= DCACHE_NEED_AUTOMOUNT; + return add_flags; +} + static void __d_instantiate(struct dentry *dentry, struct inode *inode) { + unsigned add_flags = d_flags_for_inode(inode); + spin_lock(&dentry->d_lock); - if (inode) { - if (unlikely(IS_AUTOMOUNT(inode))) - dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; + dentry->d_flags &= ~DCACHE_ENTRY_TYPE; + dentry->d_flags |= add_flags; + if (inode) hlist_add_head(&dentry->d_alias, &inode->i_dentry); - } dentry->d_inode = inode; dentry_rcuwalk_barrier(dentry); spin_unlock(&dentry->d_lock); @@ -1860,6 +1889,7 @@ struct dentry *d_obtain_alias(struct inode *inode) static const struct qstr anonstring = QSTR_INIT("/", 1); struct dentry *tmp; struct dentry *res; + unsigned add_flags; if (!inode) return ERR_PTR(-ESTALE); @@ -1885,9 +1915,11 @@ struct dentry *d_obtain_alias(struct inode *inode) } /* attach a disconnected dentry */ + add_flags = d_flags_for_inode(inode) | DCACHE_DISCONNECTED; + spin_lock(&tmp->d_lock); tmp->d_inode = inode; - tmp->d_flags |= DCACHE_DISCONNECTED; + tmp->d_flags |= add_flags; hlist_add_head(&tmp->d_alias, &inode->i_dentry); hlist_bl_lock(&tmp->d_sb->s_anon); hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); diff --git a/fs/namei.c b/fs/namei.c index e5c0118ba9f8..e1fa43346c61 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1501,18 +1501,9 @@ static void terminate_walk(struct nameidata *nd) * so we keep a cache of "no, this doesn't need follow_link" * for the common case. */ -static inline int should_follow_link(struct inode *inode, int follow) +static inline int should_follow_link(struct dentry *dentry, int follow) { - if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { - if (likely(inode->i_op->follow_link)) - return follow; - - /* This gets set once for the inode lifetime */ - spin_lock(&inode->i_lock); - inode->i_opflags |= IOP_NOFOLLOW; - spin_unlock(&inode->i_lock); - } - return 0; + return unlikely(d_is_symlink(dentry)) ? follow : 0; } static inline int walk_component(struct nameidata *nd, struct path *path, @@ -1542,7 +1533,7 @@ static inline int walk_component(struct nameidata *nd, struct path *path, if (!inode) goto out_path_put; - if (should_follow_link(inode, follow)) { + if (should_follow_link(path->dentry, follow)) { if (nd->flags & LOOKUP_RCU) { if (unlikely(unlazy_walk(nd, path->dentry))) { err = -ECHILD; @@ -1600,26 +1591,6 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd) return res; } -/* - * We really don't want to look at inode->i_op->lookup - * when we don't have to. So we keep a cache bit in - * the inode ->i_opflags field that says "yes, we can - * do lookup on this inode". - */ -static inline int can_lookup(struct inode *inode) -{ - if (likely(inode->i_opflags & IOP_LOOKUP)) - return 1; - if (likely(!inode->i_op->lookup)) - return 0; - - /* We do this once for the lifetime of the inode */ - spin_lock(&inode->i_lock); - inode->i_opflags |= IOP_LOOKUP; - spin_unlock(&inode->i_lock); - return 1; -} - /* * We can do the critical dentry name comparison and hashing * operations one word at a time, but we are limited to: @@ -1823,7 +1794,7 @@ static int link_path_walk(const char *name, struct nameidata *nd) if (err) return err; } - if (!can_lookup(nd->inode)) { + if (!d_is_directory(nd->path.dentry)) { err = -ENOTDIR; break; } @@ -1841,9 +1812,10 @@ static int path_init(int dfd, const char *name, unsigned int flags, nd->flags = flags | LOOKUP_JUMPED; nd->depth = 0; if (flags & LOOKUP_ROOT) { - struct inode *inode = nd->root.dentry->d_inode; + struct dentry *root = nd->root.dentry; + struct inode *inode = root->d_inode; if (*name) { - if (!can_lookup(inode)) + if (!d_is_directory(root)) return -ENOTDIR; retval = inode_permission(inode, MAY_EXEC); if (retval) @@ -1899,7 +1871,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, dentry = f.file->f_path.dentry; if (*name) { - if (!can_lookup(dentry->d_inode)) { + if (!d_is_directory(dentry)) { fdput(f); return -ENOTDIR; } @@ -1981,7 +1953,7 @@ static int path_lookupat(int dfd, const char *name, err = complete_walk(nd); if (!err && nd->flags & LOOKUP_DIRECTORY) { - if (!can_lookup(nd->inode)) { + if (!d_is_directory(nd->path.dentry)) { path_put(&nd->path); err = -ENOTDIR; } @@ -2273,7 +2245,7 @@ done: } path->dentry = dentry; path->mnt = mntget(nd->path.mnt); - if (should_follow_link(dentry->d_inode, nd->flags & LOOKUP_FOLLOW)) + if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) return 1; follow_mount(path); error = 0; @@ -2417,12 +2389,14 @@ static inline int check_sticky(struct inode *dir, struct inode *inode) * 10. We don't allow removal of NFS sillyrenamed files; it's handled by * nfs_async_unlink(). */ -static int may_delete(struct inode *dir,struct dentry *victim,int isdir) +static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) { + struct inode *inode = victim->d_inode; int error; - if (!victim->d_inode) + if (d_is_negative(victim)) return -ENOENT; + BUG_ON(!inode); BUG_ON(victim->d_parent->d_inode != dir); audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); @@ -2432,15 +2406,16 @@ static int may_delete(struct inode *dir,struct dentry *victim,int isdir) return error; if (IS_APPEND(dir)) return -EPERM; - if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| - IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) + + if (check_sticky(dir, inode) || IS_APPEND(inode) || + IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) return -EPERM; if (isdir) { - if (!S_ISDIR(victim->d_inode->i_mode)) + if (!d_is_directory(victim) && !d_is_autodir(victim)) return -ENOTDIR; if (IS_ROOT(victim)) return -EBUSY; - } else if (S_ISDIR(victim->d_inode->i_mode)) + } else if (d_is_directory(victim) || d_is_autodir(victim)) return -EISDIR; if (IS_DEADDIR(dir)) return -ENOENT; @@ -2974,7 +2949,7 @@ retry_lookup: /* * create/update audit record if it already exists. */ - if (path->dentry->d_inode) + if (d_is_positive(path->dentry)) audit_inode(name, path->dentry, 0); /* @@ -3003,12 +2978,12 @@ retry_lookup: finish_lookup: /* we _can_ be in RCU mode here */ error = -ENOENT; - if (!inode) { + if (d_is_negative(path->dentry)) { path_to_nameidata(path, nd); goto out; } - if (should_follow_link(inode, !symlink_ok)) { + if (should_follow_link(path->dentry, !symlink_ok)) { if (nd->flags & LOOKUP_RCU) { if (unlikely(unlazy_walk(nd, path->dentry))) { error = -ECHILD; @@ -3037,10 +3012,11 @@ finish_open: } audit_inode(name, nd->path.dentry, 0); error = -EISDIR; - if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) + if ((open_flag & O_CREAT) && + (d_is_directory(nd->path.dentry) || d_is_autodir(nd->path.dentry))) goto out; error = -ENOTDIR; - if ((nd->flags & LOOKUP_DIRECTORY) && !can_lookup(nd->inode)) + if ((nd->flags & LOOKUP_DIRECTORY) && !d_is_directory(nd->path.dentry)) goto out; if (!S_ISREG(nd->inode->i_mode)) will_truncate = false; @@ -3266,7 +3242,7 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, nd.root.mnt = mnt; nd.root.dentry = dentry; - if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) + if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) return ERR_PTR(-ELOOP); file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); @@ -3316,8 +3292,9 @@ struct dentry *kern_path_create(int dfd, const char *pathname, goto unlock; error = -EEXIST; - if (dentry->d_inode) + if (d_is_positive(dentry)) goto fail; + /* * Special case - lookup gave negative, but... we had foo/bar/ * From the vfs_mknod() POV we just have a negative dentry - @@ -3706,7 +3683,7 @@ retry: if (nd.last.name[nd.last.len]) goto slashes; inode = dentry->d_inode; - if (!inode) + if (d_is_negative(dentry)) goto slashes; ihold(inode); error = security_path_unlink(&nd.path, dentry); @@ -3731,8 +3708,12 @@ exit1: return error; slashes: - error = !dentry->d_inode ? -ENOENT : - S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; + if (d_is_negative(dentry)) + error = -ENOENT; + else if (d_is_directory(dentry) || d_is_autodir(dentry)) + error = -EISDIR; + else + error = -ENOTDIR; goto exit2; } @@ -4046,7 +4027,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) { int error; - int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); + int is_dir = d_is_directory(old_dentry) || d_is_autodir(old_dentry); const unsigned char *old_name; if (old_dentry->d_inode == new_dentry->d_inode) @@ -4134,10 +4115,10 @@ retry: goto exit3; /* source must exist */ error = -ENOENT; - if (!old_dentry->d_inode) + if (d_is_negative(old_dentry)) goto exit4; /* unless the source is a directory trailing slashes give -ENOTDIR */ - if (!S_ISDIR(old_dentry->d_inode->i_mode)) { + if (!d_is_directory(old_dentry) && !d_is_autodir(old_dentry)) { error = -ENOTDIR; if (oldnd.last.name[oldnd.last.len]) goto exit4; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 716c3760ee39..57e87e749a48 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -169,13 +169,13 @@ struct dentry_operations { */ /* d_flags entries */ -#define DCACHE_OP_HASH 0x0001 -#define DCACHE_OP_COMPARE 0x0002 -#define DCACHE_OP_REVALIDATE 0x0004 -#define DCACHE_OP_DELETE 0x0008 -#define DCACHE_OP_PRUNE 0x0010 +#define DCACHE_OP_HASH 0x00000001 +#define DCACHE_OP_COMPARE 0x00000002 +#define DCACHE_OP_REVALIDATE 0x00000004 +#define DCACHE_OP_DELETE 0x00000008 +#define DCACHE_OP_PRUNE 0x00000010 -#define DCACHE_DISCONNECTED 0x0020 +#define DCACHE_DISCONNECTED 0x00000020 /* This dentry is possibly not currently connected to the dcache tree, in * which case its parent will either be itself, or will have this flag as * well. nfsd will not use a dentry with this bit set, but will first @@ -186,30 +186,38 @@ struct dentry_operations { * dentry into place and return that dentry rather than the passed one, * typically using d_splice_alias. */ -#define DCACHE_REFERENCED 0x0040 /* Recently used, don't discard. */ -#define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */ +#define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */ +#define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */ -#define DCACHE_CANT_MOUNT 0x0100 -#define DCACHE_GENOCIDE 0x0200 -#define DCACHE_SHRINK_LIST 0x0400 +#define DCACHE_CANT_MOUNT 0x00000100 +#define DCACHE_GENOCIDE 0x00000200 +#define DCACHE_SHRINK_LIST 0x00000400 -#define DCACHE_OP_WEAK_REVALIDATE 0x0800 +#define DCACHE_OP_WEAK_REVALIDATE 0x00000800 -#define DCACHE_NFSFS_RENAMED 0x1000 +#define DCACHE_NFSFS_RENAMED 0x00001000 /* this dentry has been "silly renamed" and has to be deleted on the last * dput() */ -#define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */ -#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000 +#define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */ +#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000 /* Parent inode is watched by some fsnotify listener */ -#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */ -#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */ -#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */ +#define DCACHE_DENTRY_KILLED 0x00008000 + +#define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */ +#define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */ +#define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */ #define DCACHE_MANAGED_DENTRY \ (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) -#define DCACHE_LRU_LIST 0x80000 -#define DCACHE_DENTRY_KILLED 0x100000 +#define DCACHE_LRU_LIST 0x00080000 + +#define DCACHE_ENTRY_TYPE 0x00700000 +#define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry */ +#define DCACHE_DIRECTORY_TYPE 0x00100000 /* Normal directory */ +#define DCACHE_AUTODIR_TYPE 0x00200000 /* Lookupless directory (presumed automount) */ +#define DCACHE_SYMLINK_TYPE 0x00300000 /* Symlink */ +#define DCACHE_FILE_TYPE 0x00400000 /* Other file type */ extern seqlock_t rename_lock; @@ -394,6 +402,61 @@ static inline bool d_mountpoint(const struct dentry *dentry) return dentry->d_flags & DCACHE_MOUNTED; } +/* + * Directory cache entry type accessor functions. + */ +static inline void __d_set_type(struct dentry *dentry, unsigned type) +{ + dentry->d_flags = (dentry->d_flags & ~DCACHE_ENTRY_TYPE) | type; +} + +static inline void __d_clear_type(struct dentry *dentry) +{ + __d_set_type(dentry, DCACHE_MISS_TYPE); +} + +static inline void d_set_type(struct dentry *dentry, unsigned type) +{ + spin_lock(&dentry->d_lock); + __d_set_type(dentry, type); + spin_unlock(&dentry->d_lock); +} + +static inline unsigned __d_entry_type(const struct dentry *dentry) +{ + return dentry->d_flags & DCACHE_ENTRY_TYPE; +} + +static inline bool d_is_directory(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE; +} + +static inline bool d_is_autodir(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE; +} + +static inline bool d_is_symlink(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE; +} + +static inline bool d_is_file(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_FILE_TYPE; +} + +static inline bool d_is_negative(const struct dentry *dentry) +{ + return __d_entry_type(dentry) == DCACHE_MISS_TYPE; +} + +static inline bool d_is_positive(const struct dentry *dentry) +{ + return !d_is_negative(dentry); +} + extern int sysctl_vfs_cache_pressure; static inline unsigned long vfs_pressure_ratio(unsigned long val) -- 2.20.1