[02/18] fs: add get_acl helper

Commit Message

Christoph Hellwig Dec. 11, 2013, 10:42 a.m. UTC

Factor out the code to get an ACL either from the inode or disk from
check_acl, so that it can be used elsewhere later on.

Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Jan Kara <[e-mail]>
---
 fs/namei.c                |   24 +++---------------------
 fs/posix_acl.c            |   26 ++++++++++++++++++++++++++
 include/linux/posix_acl.h |    2 ++
 3 files changed, 31 insertions(+), 21 deletions(-)

Comments

Andreas Gruenbacher Dec. 12, 2013, 7:06 p.m. UTC | #1

Christoph,

> +struct posix_acl *get_acl(struct inode *inode, int type)
> +{
> +	struct posix_acl *acl;
> +
> +	acl = get_cached_acl(inode, type);
> +	if (acl != ACL_NOT_CACHED)
> +		return acl;
> +
> +	if (!IS_POSIXACL(inode))
> +		return NULL;
> +
> +	/*
> +	 * A filesystem can force a ACL callback by just never filling the
> +	 * ACL cache. But normally you'd fill the cache either at inode
> +	 * instantiation time, or on the first ->get_acl call.
> +	 *
> +	 * If the filesystem doesn't have a get_acl() function at all, we'll
> +	 * just create the negative cache entry.
> +	 */
> +	if (!inode->i_op->get_acl) {
> +		set_cached_acl(inode, type, NULL);
> +		return ERR_PTR(-EAGAIN);

The function should return NULL here.

Andreas
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Christoph Hellwig Dec. 12, 2013, 9:04 p.m. UTC | #2

On Thu, Dec 12, 2013 at 08:06:09PM +0100, Andreas Gruenbacher wrote:
> > +	/*
> > +	 * A filesystem can force a ACL callback by just never filling the
> > +	 * ACL cache. But normally you'd fill the cache either at inode
> > +	 * instantiation time, or on the first ->get_acl call.
> > +	 *
> > +	 * If the filesystem doesn't have a get_acl() function at all, we'll
> > +	 * just create the negative cache entry.
> > +	 */
> > +	if (!inode->i_op->get_acl) {
> > +		set_cached_acl(inode, type, NULL);
> > +		return ERR_PTR(-EAGAIN);
> 
> The function should return NULL here.

Indeed.  EAGAIN is the convention check_acl() in fs/namei.c uses,
but it will return that automatically if we just return NULL here.
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Patch

diff --git a/fs/namei.c b/fs/namei.c
index c53d3a9..8acd1e8 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -235,27 +235,9 @@  static int check_acl(struct inode *inode, int mask)
 	        return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
 	}
 
-	acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
-
-	/*
-	 * A filesystem can force a ACL callback by just never filling the
-	 * ACL cache. But normally you'd fill the cache either at inode
-	 * instantiation time, or on the first ->get_acl call.
-	 *
-	 * If the filesystem doesn't have a get_acl() function at all, we'll
-	 * just create the negative cache entry.
-	 */
-	if (acl == ACL_NOT_CACHED) {
-	        if (inode->i_op->get_acl) {
-			acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS);
-			if (IS_ERR(acl))
-				return PTR_ERR(acl);
-		} else {
-		        set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
-		        return -EAGAIN;
-		}
-	}
-
+	acl = get_acl(inode, ACL_TYPE_ACCESS);
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
 	if (acl) {
 	        int error = posix_acl_permission(inode, acl, mask);
 	        posix_acl_release(acl);
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 8bd2135..f2c48f8 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -418,3 +418,29 @@  posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
 	return err;
 }
 EXPORT_SYMBOL(posix_acl_chmod);
+
+struct posix_acl *get_acl(struct inode *inode, int type)
+{
+	struct posix_acl *acl;
+
+	acl = get_cached_acl(inode, type);
+	if (acl != ACL_NOT_CACHED)
+		return acl;
+
+	if (!IS_POSIXACL(inode))
+		return NULL;
+
+	/*
+	 * A filesystem can force a ACL callback by just never filling the
+	 * ACL cache. But normally you'd fill the cache either at inode
+	 * instantiation time, or on the first ->get_acl call.
+	 *
+	 * If the filesystem doesn't have a get_acl() function at all, we'll
+	 * just create the negative cache entry.
+	 */
+	if (!inode->i_op->get_acl) {
+		set_cached_acl(inode, type, NULL);
+		return ERR_PTR(-EAGAIN);
+	}
+	return inode->i_op->get_acl(inode, type);
+}
diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index 7931efe..a8d9918 100644
--- a/include/linux/posix_acl.h
+++ b/include/linux/posix_acl.h
@@ -175,4 +175,6 @@  static inline void cache_no_acl(struct inode *inode)
 #endif
 }
 
+struct posix_acl *get_acl(struct inode *inode, int type);
+
 #endif  /* __LINUX_POSIX_ACL_H */