Re: [PATCH 6/9] xfs: Add xfs_has_attr and subroutines

Allison Henderson <allison.henderson@xxxxxxxxxx> · Mon, 22 Apr 2019 15:01:22 -0700

On 4/22/19 6:00 AM, Brian Foster wrote:
On Fri, Apr 12, 2019 at 03:50:33PM -0700, Allison Henderson wrote:
This patch adds a new functions to check for the existence of
an attribute.  Subroutines are also added to handle the cases
of leaf blocks, nodes or shortform.  We will need this later
for delayed attributes since delayed operations cannot return
error codes.

Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
---
  fs/xfs/libxfs/xfs_attr.c      | 78 +++++++++++++++++++++++++++++++++++++++++++
  fs/xfs/libxfs/xfs_attr.h      |  1 +
  fs/xfs/libxfs/xfs_attr_leaf.c | 33 ++++++++++++++++++
  fs/xfs/libxfs/xfs_attr_leaf.h |  1 +
  4 files changed, 113 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index c3477fa7..0042708 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -53,6 +53,7 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);
  STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
  STATIC int xfs_attr_leaf_addname(xfs_da_args_t *args, bool roll_trans);
  STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args, bool roll_trans);
+STATIC int xfs_leaf_has_attr(xfs_da_args_t *args);
  
  /*
   * Internal routines when attribute list is more than one block.
@@ -60,6 +61,7 @@ STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args, bool roll_trans);
  STATIC int xfs_attr_node_get(xfs_da_args_t *args);
  STATIC int xfs_attr_node_addname(xfs_da_args_t *args, bool roll_trans);
  STATIC int xfs_attr_node_removename(xfs_da_args_t *args, bool roll_trans);
+STATIC int xfs_attr_node_hasname(xfs_da_args_t *args);
  STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
  STATIC int xfs_attr_refillstate(xfs_da_state_t *state);
  
@@ -301,6 +303,29 @@ xfs_attr_set_args(
  }
  
  /*
+ * Return successful if attr is found, or ENOATTR if not
+ */
+int
+xfs_has_attr(
+	struct xfs_da_args      *args)
+{
+	struct xfs_inode        *dp = args->dp;
+	int                     error;
+
+	if (!xfs_inode_hasattr(dp))
+		error = -ENOATTR;
+	else if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL) {
+		ASSERT(dp->i_afp->if_flags & XFS_IFINLINE);
+		error = xfs_shortform_has_attr(args);
+	} else if (xfs_bmap_one_block(dp, XFS_ATTR_FORK))
+		error = xfs_leaf_has_attr(args);
+	else
+		error = xfs_attr_node_hasname(args);

I think it's usually expected to keep the {} braces around each branch
of a multi-branch if/else when at least one branch has multiple lines.

Also, I see that at least some of this code is pulled from existing
xattr functions. For example, the xfs_shortform_has_attr() code
currently exists in xfs_attr_shortform_remove(),
xfs_attr_shortform_add(), etc. Similar for xfs_leaf_has_attr() and
xfs_attr_leaf_removename(), etc.

Rather than just adding new, not yet used functions, can we turn this
patch more into a refactor where these new functions are reused by
existing code where applicable? That reduces duplication and also
facilitates review.

Brian

Sure, I will see if I can factor out the common code and consolidate 
things a bit.

Allison


+
+	return error;
+}
+
+/*
   * Remove the attribute specified in @args.
   */
  int
@@ -836,6 +861,29 @@ xfs_attr_leaf_addname(
  }
  
  /*
+ * Return successful if attr is found, or ENOATTR if not
+ */
+STATIC int
+xfs_leaf_has_attr(
+	struct xfs_da_args      *args)
+{
+	struct xfs_buf          *bp;
+	int                     error = 0;
+
+	args->blkno = 0;
+	error = xfs_attr3_leaf_read(args->trans, args->dp,
+			args->blkno, -1, &bp);
+	if (error)
+		return error;
+
+	error = xfs_attr3_leaf_lookup_int(bp, args);
+	error = (error == -ENOATTR) ? -ENOATTR : 0;
+	xfs_trans_brelse(args->trans, bp);
+
+	return error;
+}
+
+/*
   * Remove a name from the leaf attribute list structure
   *
   * This leaf block cannot have a "remote" value, we only call this routine
@@ -1166,6 +1214,36 @@ xfs_attr_node_addname(
  }
  
  /*
+ * Return successful if attr is found, or ENOATTR if not
+ */
+STATIC int
+xfs_attr_node_hasname(
+	struct xfs_da_args	*args)
+{
+	struct xfs_da_state	*state;
+	struct xfs_inode	*dp;
+	int			retval, error;
+
+	/*
+	 * Tie a string around our finger to remind us where we are.
+	 */
+	dp = args->dp;
+	state = xfs_da_state_alloc();
+	state->args = args;
+	state->mp = dp->i_mount;
+
+	/*
+	 * Search to see if name exists, and get back a pointer to it.
+	 */
+	error = xfs_da3_node_lookup_int(state, &retval);
+	if (error || (retval != -EEXIST)) {
+		if (error == 0)
+			error = retval;
+	}
+	return error;
+}
+
+/*
   * Remove a name from a B-tree attribute list.
   *
   * This will involve walking down the Btree, and may involve joining
diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
index 83b3621..974c963 100644
--- a/fs/xfs/libxfs/xfs_attr.h
+++ b/fs/xfs/libxfs/xfs_attr.h
@@ -168,6 +168,7 @@ int xfs_attr_set_args(struct xfs_da_args *args, struct xfs_buf **leaf_bp,
  		 bool roll_trans);
  int xfs_attr_remove(struct xfs_inode *dp, const unsigned char *name,
  		    size_t namelen, int flags);
+int xfs_has_attr(struct xfs_da_args *args);
  int xfs_attr_remove_args(struct xfs_da_args *args, bool roll_trans);
  int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
  		  int flags, struct attrlist_cursor_kern *cursor);
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 128bfe9..e9f2f53 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -622,6 +622,39 @@ xfs_attr_fork_remove(
  }
  
  /*
+ * Return successful if attr is found, or ENOATTR if not
+ */
+int
+xfs_shortform_has_attr(
+	struct xfs_da_args	 *args)
+{
+	struct xfs_attr_shortform *sf;
+	struct xfs_attr_sf_entry *sfe;
+	int			base = sizeof(struct xfs_attr_sf_hdr);
+	int			size = 0;
+	int			end;
+	int			i;
+
+	sf = (struct xfs_attr_shortform *)args->dp->i_afp->if_u1.if_data;
+	sfe = &sf->list[0];
+	end = sf->hdr.count;
+	for (i = 0; i < end; sfe = XFS_ATTR_SF_NEXTENTRY(sfe),
+			base += size, i++) {
+		size = XFS_ATTR_SF_ENTSIZE(sfe);
+		if (sfe->namelen != args->namelen)
+			continue;
+		if (memcmp(sfe->nameval, args->name, args->namelen) != 0)
+			continue;
+		if (!xfs_attr_namesp_match(args->flags, sfe->flags))
+			continue;
+		break;
+	}
+	if (i == end)
+		return -ENOATTR;
+	return 0;
+}
+
+/*
   * Remove an attribute from the shortform attribute list structure.
   */
  int
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h
index 9d830ec..98dd169 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.h
+++ b/fs/xfs/libxfs/xfs_attr_leaf.h
@@ -39,6 +39,7 @@ int	xfs_attr_shortform_getvalue(struct xfs_da_args *args);
  int	xfs_attr_shortform_to_leaf(struct xfs_da_args *args,
  			struct xfs_buf **leaf_bp);
  int	xfs_attr_shortform_remove(struct xfs_da_args *args);
+int	xfs_shortform_has_attr(struct xfs_da_args *args);
  int	xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
  int	xfs_attr_shortform_bytesfit(struct xfs_inode *dp, int bytes);
  xfs_failaddr_t xfs_attr_shortform_verify(struct xfs_inode *ip);
--
2.7.4







