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-rw-r--r--fs/namei.c118
1 files changed, 88 insertions, 30 deletions
diff --git a/fs/namei.c b/fs/namei.c
index f8c69d373793..f4788365ea22 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -179,19 +179,14 @@ static int check_acl(struct inode *inode, int mask)
#ifdef CONFIG_FS_POSIX_ACL
struct posix_acl *acl;
- /*
- * Under RCU walk, we cannot even do a "get_cached_acl()",
- * because that involves locking and getting a refcount on
- * a cached ACL.
- *
- * So the only case we handle during RCU walking is the
- * case of a cached "no ACL at all", which needs no locks
- * or refcounts.
- */
if (mask & MAY_NOT_BLOCK) {
- if (negative_cached_acl(inode, ACL_TYPE_ACCESS))
+ acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
+ if (!acl)
return -EAGAIN;
- return -ECHILD;
+ /* no ->get_acl() calls in RCU mode... */
+ if (acl == ACL_NOT_CACHED)
+ return -ECHILD;
+ return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
}
acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
@@ -313,6 +308,26 @@ int generic_permission(struct inode *inode, int mask)
return -EACCES;
}
+/*
+ * We _really_ want to just do "generic_permission()" without
+ * even looking at the inode->i_op values. So we keep a cache
+ * flag in inode->i_opflags, that says "this has not special
+ * permission function, use the fast case".
+ */
+static inline int do_inode_permission(struct inode *inode, int mask)
+{
+ if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
+ if (likely(inode->i_op->permission))
+ return inode->i_op->permission(inode, mask);
+
+ /* This gets set once for the inode lifetime */
+ spin_lock(&inode->i_lock);
+ inode->i_opflags |= IOP_FASTPERM;
+ spin_unlock(&inode->i_lock);
+ }
+ return generic_permission(inode, mask);
+}
+
/**
* inode_permission - check for access rights to a given inode
* @inode: inode to check permission on
@@ -327,7 +342,7 @@ int inode_permission(struct inode *inode, int mask)
{
int retval;
- if (mask & MAY_WRITE) {
+ if (unlikely(mask & MAY_WRITE)) {
umode_t mode = inode->i_mode;
/*
@@ -344,11 +359,7 @@ int inode_permission(struct inode *inode, int mask)
return -EACCES;
}
- if (inode->i_op->permission)
- retval = inode->i_op->permission(inode, mask);
- else
- retval = generic_permission(inode, mask);
-
+ retval = do_inode_permission(inode, mask);
if (retval)
return retval;
@@ -716,17 +727,20 @@ static int follow_automount(struct path *path, unsigned flags,
if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT))
return -EISDIR; /* we actually want to stop here */
- /* We want to mount if someone is trying to open/create a file of any
- * type under the mountpoint, wants to traverse through the mountpoint
- * or wants to open the mounted directory.
+ /* We don't want to mount if someone's just doing a stat -
+ * unless they're stat'ing a directory and appended a '/' to
+ * the name.
*
- * We don't want to mount if someone's just doing a stat and they've
- * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and
- * appended a '/' to the name.
+ * We do, however, want to mount if someone wants to open or
+ * create a file of any type under the mountpoint, wants to
+ * traverse through the mountpoint or wants to open the
+ * mounted directory. Also, autofs may mark negative dentries
+ * as being automount points. These will need the attentions
+ * of the daemon to instantiate them before they can be used.
*/
- if (!(flags & LOOKUP_FOLLOW) &&
- !(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
- LOOKUP_OPEN | LOOKUP_CREATE)))
+ if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
+ LOOKUP_OPEN | LOOKUP_CREATE)) &&
+ path->dentry->d_inode)
return -EISDIR;
current->total_link_count++;
@@ -1244,6 +1258,26 @@ static void terminate_walk(struct nameidata *nd)
}
}
+/*
+ * Do we need to follow links? We _really_ want to be able
+ * to do this check without having to look at inode->i_op,
+ * 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)
+{
+ 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;
+}
+
static inline int walk_component(struct nameidata *nd, struct path *path,
struct qstr *name, int type, int follow)
{
@@ -1266,7 +1300,7 @@ static inline int walk_component(struct nameidata *nd, struct path *path,
terminate_walk(nd);
return -ENOENT;
}
- if (unlikely(inode->i_op->follow_link) && follow) {
+ if (should_follow_link(inode, follow)) {
if (nd->flags & LOOKUP_RCU) {
if (unlikely(unlazy_walk(nd, path->dentry))) {
terminate_walk(nd);
@@ -1319,6 +1353,26 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd)
}
/*
+ * 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;
+}
+
+/*
* Name resolution.
* This is the basic name resolution function, turning a pathname into
* the final dentry. We expect 'base' to be positive and a directory.
@@ -1397,10 +1451,10 @@ static int link_path_walk(const char *name, struct nameidata *nd)
if (err)
return err;
}
+ if (can_lookup(nd->inode))
+ continue;
err = -ENOTDIR;
- if (!nd->inode->i_op->lookup)
- break;
- continue;
+ break;
/* here ends the main loop */
last_component:
@@ -2562,6 +2616,7 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
if (!dir->i_op->rmdir)
return -EPERM;
+ dget(dentry);
mutex_lock(&dentry->d_inode->i_mutex);
error = -EBUSY;
@@ -2582,6 +2637,7 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
out:
mutex_unlock(&dentry->d_inode->i_mutex);
+ dput(dentry);
if (!error)
d_delete(dentry);
return error;
@@ -2971,6 +3027,7 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
if (error)
return error;
+ dget(new_dentry);
if (target)
mutex_lock(&target->i_mutex);
@@ -2991,6 +3048,7 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
out:
if (target)
mutex_unlock(&target->i_mutex);
+ dput(new_dentry);
if (!error)
if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
d_move(old_dentry,new_dentry);
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-20 06:29:22 +0000