tmpfs: Use xattr handler infrastructure

Use the VFS xattr handler infrastructure and get rid of similar code in
the filesystem.  For implementing shmem_xattr_handler_set, we need a
version of simple_xattr_set which removes the attribute when value is
NULL.  Use this to implement kernfs_iop_removexattr as well.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 756dd56..f97e1f7 100644 (file)
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -205,7 +205,7 @@ int kernfs_iop_removexattr(struct dentry *dentry, const char *name)
        if (!attrs)
                return -ENOMEM;
 
-       return simple_xattr_remove(&attrs->xattrs, name);
+       return simple_xattr_set(&attrs->xattrs, name, NULL, 0, XATTR_REPLACE);
 }
 
 ssize_t kernfs_iop_getxattr(struct dentry *dentry, const char *name, void *buf,

diff --git a/fs/xattr.c b/fs/xattr.c
index 418ad69..4ef8b37 100644 (file)
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -851,8 +851,22 @@ int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
        return ret;
 }
 
-static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
-                             const void *value, size_t size, int flags)
+/**
+ * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
+ * @xattrs: target simple_xattr list
+ * @name: name of the extended attribute
+ * @value: value of the xattr. If %NULL, will remove the attribute.
+ * @size: size of the new xattr
+ * @flags: %XATTR_{CREATE|REPLACE}
+ *
+ * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
+ * with -EEXIST.  If %XATTR_REPLACE is set, the xattr should exist;
+ * otherwise, fails with -ENODATA.
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
+                    const void *value, size_t size, int flags)
 {
        struct simple_xattr *xattr;
        struct simple_xattr *new_xattr = NULL;
@@ -902,36 +916,6 @@ out:
 
 }
 
-/**
- * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
- * @xattrs: target simple_xattr list
- * @name: name of the new extended attribute
- * @value: value of the new xattr. If %NULL, will remove the attribute
- * @size: size of the new xattr
- * @flags: %XATTR_{CREATE|REPLACE}
- *
- * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
- * with -EEXIST.  If %XATTR_REPLACE is set, the xattr should exist;
- * otherwise, fails with -ENODATA.
- *
- * Returns 0 on success, -errno on failure.
- */
-int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
-                    const void *value, size_t size, int flags)
-{
-       if (size == 0)
-               value = ""; /* empty EA, do not remove */
-       return __simple_xattr_set(xattrs, name, value, size, flags);
-}
-
-/*
- * xattr REMOVE operation for in-memory/pseudo filesystems
- */
-int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
-{
-       return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE);
-}
-
 static bool xattr_is_trusted(const char *name)
 {
        return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);

diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index 03c847f..4dd40cb 100644 (file)
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -104,9 +104,7 @@ int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
                     void *buffer, size_t size);
 int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
                     const void *value, size_t size, int flags);
-int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name);
-ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
-                         size_t size);
+ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer, size_t size);
 void simple_xattr_list_add(struct simple_xattrs *xattrs,
                           struct simple_xattr *new_xattr);
 

diff --git a/mm/shmem.c b/mm/shmem.c
index 9187eee..fdfe6c8 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2561,94 +2561,47 @@ static int shmem_initxattrs(struct inode *inode,
        return 0;
 }
 
-static const struct xattr_handler *shmem_xattr_handlers[] = {
-#ifdef CONFIG_TMPFS_POSIX_ACL
-       &posix_acl_access_xattr_handler,
-       &posix_acl_default_xattr_handler,
-#endif
-       NULL
-};
-
-static int shmem_xattr_validate(const char *name)
-{
-       struct { const char *prefix; size_t len; } arr[] = {
-               { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
-               { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
-       };
-       int i;
-
-       for (i = 0; i < ARRAY_SIZE(arr); i++) {
-               size_t preflen = arr[i].len;
-               if (strncmp(name, arr[i].prefix, preflen) == 0) {
-                       if (!name[preflen])
-                               return -EINVAL;
-                       return 0;
-               }
-       }
-       return -EOPNOTSUPP;
-}
-
-static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
-                             void *buffer, size_t size)
+static int shmem_xattr_handler_get(const struct xattr_handler *handler,
+                                  struct dentry *dentry, const char *name,
+                                  void *buffer, size_t size)
 {
        struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
-       int err;
-
-       /*
-        * If this is a request for a synthetic attribute in the system.*
-        * namespace use the generic infrastructure to resolve a handler
-        * for it via sb->s_xattr.
-        */
-       if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-               return generic_getxattr(dentry, name, buffer, size);
-
-       err = shmem_xattr_validate(name);
-       if (err)
-               return err;
 
+       name = xattr_full_name(handler, name);
        return simple_xattr_get(&info->xattrs, name, buffer, size);
 }
 
-static int shmem_setxattr(struct dentry *dentry, const char *name,
-                         const void *value, size_t size, int flags)
+static int shmem_xattr_handler_set(const struct xattr_handler *handler,
+                                  struct dentry *dentry, const char *name,
+                                  const void *value, size_t size, int flags)
 {
        struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
-       int err;
-
-       /*
-        * If this is a request for a synthetic attribute in the system.*
-        * namespace use the generic infrastructure to resolve a handler
-        * for it via sb->s_xattr.
-        */
-       if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-               return generic_setxattr(dentry, name, value, size, flags);
-
-       err = shmem_xattr_validate(name);
-       if (err)
-               return err;
 
+       name = xattr_full_name(handler, name);
        return simple_xattr_set(&info->xattrs, name, value, size, flags);
 }
 
-static int shmem_removexattr(struct dentry *dentry, const char *name)
-{
-       struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
-       int err;
-
-       /*
-        * If this is a request for a synthetic attribute in the system.*
-        * namespace use the generic infrastructure to resolve a handler
-        * for it via sb->s_xattr.
-        */
-       if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-               return generic_removexattr(dentry, name);
+static const struct xattr_handler shmem_security_xattr_handler = {
+       .prefix = XATTR_SECURITY_PREFIX,
+       .get = shmem_xattr_handler_get,
+       .set = shmem_xattr_handler_set,
+};
 
-       err = shmem_xattr_validate(name);
-       if (err)
-               return err;
+static const struct xattr_handler shmem_trusted_xattr_handler = {
+       .prefix = XATTR_TRUSTED_PREFIX,
+       .get = shmem_xattr_handler_get,
+       .set = shmem_xattr_handler_set,
+};
 
-       return simple_xattr_remove(&info->xattrs, name);
-}
+static const struct xattr_handler *shmem_xattr_handlers[] = {
+#ifdef CONFIG_TMPFS_POSIX_ACL
+       &posix_acl_access_xattr_handler,
+       &posix_acl_default_xattr_handler,
+#endif
+       &shmem_security_xattr_handler,
+       &shmem_trusted_xattr_handler,
+       NULL
+};
 
 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
 {
@@ -2661,10 +2614,10 @@ static const struct inode_operations shmem_short_symlink_operations = {
        .readlink       = generic_readlink,
        .follow_link    = simple_follow_link,
 #ifdef CONFIG_TMPFS_XATTR
-       .setxattr       = shmem_setxattr,
-       .getxattr       = shmem_getxattr,
+       .setxattr       = generic_setxattr,
+       .getxattr       = generic_getxattr,
        .listxattr      = shmem_listxattr,
-       .removexattr    = shmem_removexattr,
+       .removexattr    = generic_removexattr,
 #endif
 };
 
@@ -2673,10 +2626,10 @@ static const struct inode_operations shmem_symlink_inode_operations = {
        .follow_link    = shmem_follow_link,
        .put_link       = shmem_put_link,
 #ifdef CONFIG_TMPFS_XATTR
-       .setxattr       = shmem_setxattr,
-       .getxattr       = shmem_getxattr,
+       .setxattr       = generic_setxattr,
+       .getxattr       = generic_getxattr,
        .listxattr      = shmem_listxattr,
-       .removexattr    = shmem_removexattr,
+       .removexattr    = generic_removexattr,
 #endif
 };
 
@@ -3148,10 +3101,10 @@ static const struct inode_operations shmem_inode_operations = {
        .getattr        = shmem_getattr,
        .setattr        = shmem_setattr,
 #ifdef CONFIG_TMPFS_XATTR
-       .setxattr       = shmem_setxattr,
-       .getxattr       = shmem_getxattr,
+       .setxattr       = generic_setxattr,
+       .getxattr       = generic_getxattr,
        .listxattr      = shmem_listxattr,
-       .removexattr    = shmem_removexattr,
+       .removexattr    = generic_removexattr,
        .set_acl        = simple_set_acl,
 #endif
 };
@@ -3170,10 +3123,10 @@ static const struct inode_operations shmem_dir_inode_operations = {
        .tmpfile        = shmem_tmpfile,
 #endif
 #ifdef CONFIG_TMPFS_XATTR
-       .setxattr       = shmem_setxattr,
-       .getxattr       = shmem_getxattr,
+       .setxattr       = generic_setxattr,
+       .getxattr       = generic_getxattr,
        .listxattr      = shmem_listxattr,
-       .removexattr    = shmem_removexattr,
+       .removexattr    = generic_removexattr,
 #endif
 #ifdef CONFIG_TMPFS_POSIX_ACL
        .setattr        = shmem_setattr,
@@ -3183,10 +3136,10 @@ static const struct inode_operations shmem_dir_inode_operations = {
 
 static const struct inode_operations shmem_special_inode_operations = {
 #ifdef CONFIG_TMPFS_XATTR
-       .setxattr       = shmem_setxattr,
-       .getxattr       = shmem_getxattr,
+       .setxattr       = generic_setxattr,
+       .getxattr       = generic_getxattr,
        .listxattr      = shmem_listxattr,
-       .removexattr    = shmem_removexattr,
+       .removexattr    = generic_removexattr,
 #endif
 #ifdef CONFIG_TMPFS_POSIX_ACL
        .setattr        = shmem_setattr,