xfs: (re-)implement FIEMAP_FLAG_XATTR

Use a special read-only iomap_ops implementation to support fiemap on
the attr fork.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

3 files changed, 54 insertions, 1 deletions

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 1cce760399a2..697c8fd4200f 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1106,3 +1106,48 @@ struct iomap_ops xfs_iomap_ops = {
         .iomap_begin            = xfs_file_iomap_begin,
         .iomap_end              = xfs_file_iomap_end,
 };
+
+static int
+xfs_xattr_iomap_begin(
+        struct inode            *inode,
+        loff_t                  offset,
+        loff_t                  length,
+        unsigned                flags,
+        struct iomap            *iomap)
+{
+        struct xfs_inode        *ip = XFS_I(inode);
+        struct xfs_mount        *mp = ip->i_mount;
+        xfs_fileoff_t           offset_fsb = XFS_B_TO_FSBT(mp, offset);
+        xfs_fileoff_t           end_fsb = XFS_B_TO_FSB(mp, offset + length);
+        struct xfs_bmbt_irec    imap;
+        int                     nimaps = 1, error = 0;
+        unsigned                lockmode;
+
+        if (XFS_FORCED_SHUTDOWN(mp))
+                return -EIO;
+
+        lockmode = xfs_ilock_data_map_shared(ip);
+
+        /* if there are no attribute fork or extents, return ENOENT */
+        if (XFS_IFORK_Q(ip) || !ip->i_d.di_anextents) {
+                error = -ENOENT;
+                goto out_unlock;
+        }
+
+        ASSERT(ip->i_d.di_aformat != XFS_DINODE_FMT_LOCAL);
+        error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
+                               &nimaps, XFS_BMAPI_ENTIRE | XFS_BMAPI_ATTRFORK);
+out_unlock:
+        xfs_iunlock(ip, lockmode);
+
+        if (!error) {
+                ASSERT(nimaps);
+                xfs_bmbt_to_iomap(ip, iomap, &imap);
+        }
+
+        return error;
+}
+
+struct iomap_ops xfs_xattr_iomap_ops = {
+        .iomap_begin            = xfs_xattr_iomap_begin,
+};
diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h
index e066d045e2ff..fb8aca3d69ab 100644
--- a/fs/xfs/xfs_iomap.h
+++ b/fs/xfs/xfs_iomap.h
@@ -35,5 +35,6 @@ void xfs_bmbt_to_iomap(struct xfs_inode *, struct iomap *,
                 struct xfs_bmbt_irec *);
 
 extern struct iomap_ops xfs_iomap_ops;
+extern struct iomap_ops xfs_xattr_iomap_ops;
 
 #endif /* __XFS_IOMAP_H__*/
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index ab820f84ed50..b24c3102fa93 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1009,7 +1009,14 @@ xfs_vn_fiemap(
         int                     error;
 
         xfs_ilock(XFS_I(inode), XFS_IOLOCK_SHARED);
-        error = iomap_fiemap(inode, fieinfo, start, length, &xfs_iomap_ops);
+        if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
+                fieinfo->fi_flags &= ~FIEMAP_FLAG_XATTR;
+                error = iomap_fiemap(inode, fieinfo, start, length,
+                                &xfs_xattr_iomap_ops);
+        } else {
+                error = iomap_fiemap(inode, fieinfo, start, length,
+                                &xfs_iomap_ops);
+        }
         xfs_iunlock(XFS_I(inode), XFS_IOLOCK_SHARED);
 
         return error;