autofs: use inode permission method for write access

Patch series "autofs: misc patches".

This series contains several patches that resulted mostly from comments
made by Al Viro (quite a long time ago now).

This patch (of 5):

Eliminate some code duplication from mkdir/rmdir/symlink/unlink methods by
using the inode operation .permission().

Link: https://lkml.kernel.org/r/165724445154.30914.10970894936827635879.stgit@donald.themaw.net
Link: https://lkml.kernel.org/r/165724458096.30914.13499431569758625806.stgit@donald.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/autofs/root.c b/fs/autofs/root.c
index 91fe4548c25657fda73be2ea8054967ba047fc26..fef6ed9910221d763b47e8a83b29103e9a5ad23c 100644 (file)
--- a/fs/autofs/root.c
+++ b/fs/autofs/root.c
@@ -10,6 +10,7 @@
 
 #include "autofs_i.h"
 
+static int autofs_dir_permission(struct user_namespace *, struct inode *, int);
 static int autofs_dir_symlink(struct user_namespace *, struct inode *,
                              struct dentry *, const char *);
 static int autofs_dir_unlink(struct inode *, struct dentry *);
@@ -50,6 +51,7 @@ const struct file_operations autofs_dir_operations = {
 
 const struct inode_operations autofs_dir_inode_operations = {
        .lookup         = autofs_lookup,
+       .permission     = autofs_dir_permission,
        .unlink         = autofs_dir_unlink,
        .symlink        = autofs_dir_symlink,
        .mkdir          = autofs_dir_mkdir,
@@ -526,11 +528,30 @@ static struct dentry *autofs_lookup(struct inode *dir,
        return NULL;
 }
 
+static int autofs_dir_permission(struct user_namespace *mnt_userns,
+                                struct inode *inode, int mask)
+{
+       if (mask & MAY_WRITE) {
+               struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
+
+               if (!autofs_oz_mode(sbi))
+                       return -EACCES;
+
+               /* autofs_oz_mode() needs to allow path walks when the
+                * autofs mount is catatonic but the state of an autofs
+                * file system needs to be preserved over restarts.
+                */
+               if (sbi->flags & AUTOFS_SBI_CATATONIC)
+                       return -EACCES;
+       }
+
+       return generic_permission(mnt_userns, inode, mask);
+}
+
 static int autofs_dir_symlink(struct user_namespace *mnt_userns,
                              struct inode *dir, struct dentry *dentry,
                              const char *symname)
 {
-       struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
        struct autofs_info *ino = autofs_dentry_ino(dentry);
        struct autofs_info *p_ino;
        struct inode *inode;
@@ -539,16 +560,6 @@ static int autofs_dir_symlink(struct user_namespace *mnt_userns,
 
        pr_debug("%s <- %pd\n", symname, dentry);
 
-       if (!autofs_oz_mode(sbi))
-               return -EACCES;
-
-       /* autofs_oz_mode() needs to allow path walks when the
-        * autofs mount is catatonic but the state of an autofs
-        * file system needs to be preserved over restarts.
-        */
-       if (sbi->flags & AUTOFS_SBI_CATATONIC)
-               return -EACCES;
-
        BUG_ON(!ino);
 
        autofs_clean_ino(ino);
@@ -601,16 +612,6 @@ static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry)
        struct autofs_info *ino = autofs_dentry_ino(dentry);
        struct autofs_info *p_ino;
 
-       if (!autofs_oz_mode(sbi))
-               return -EACCES;
-
-       /* autofs_oz_mode() needs to allow path walks when the
-        * autofs mount is catatonic but the state of an autofs
-        * file system needs to be preserved over restarts.
-        */
-       if (sbi->flags & AUTOFS_SBI_CATATONIC)
-               return -EACCES;
-
        ino->count--;
        p_ino = autofs_dentry_ino(dentry->d_parent);
        p_ino->count--;
@@ -683,16 +684,6 @@ static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
 
        pr_debug("dentry %p, removing %pd\n", dentry, dentry);
 
-       if (!autofs_oz_mode(sbi))
-               return -EACCES;
-
-       /* autofs_oz_mode() needs to allow path walks when the
-        * autofs mount is catatonic but the state of an autofs
-        * file system needs to be preserved over restarts.
-        */
-       if (sbi->flags & AUTOFS_SBI_CATATONIC)
-               return -EACCES;
-
        if (ino->count != 1)
                return -ENOTEMPTY;
 
@@ -726,16 +717,6 @@ static int autofs_dir_mkdir(struct user_namespace *mnt_userns,
        struct autofs_info *p_ino;
        struct inode *inode;
 
-       if (!autofs_oz_mode(sbi))
-               return -EACCES;
-
-       /* autofs_oz_mode() needs to allow path walks when the
-        * autofs mount is catatonic but the state of an autofs
-        * file system needs to be preserved over restarts.
-        */
-       if (sbi->flags & AUTOFS_SBI_CATATONIC)
-               return -EACCES;
-
        pr_debug("dentry %p, creating %pd\n", dentry, dentry);
 
        BUG_ON(!ino);