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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 <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2013-09-12 19:22:53 +01:00 committed by Al Viro
parent afabada957
commit b18825a7c8
3 changed files with 158 additions and 82 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
fs/dcache.c
View File

@ -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);

95
fs/namei.c
View File

@ -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;

103
include/linux/dcache.h
View File

@ -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)