ext4: make ext4_ind_map_blocks work with fiemap

For indirect block mapping if the i_block > max supported block in inode
then ext4_ind_map_blocks() returns a -EIO error. But in case of fiemap
this could be a valid query to ->iomap_begin call.
So check if the offset >= s_bitmap_maxbytes in ext4_iomap_begin_report(),
then simply skip calling ext4_map_blocks().

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/87fa0ddc5967fa707656212a3b66a7233425325c.1582880246.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 07ca260..f6aebb7 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3546,12 +3546,28 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
        map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
                          EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
 
+       /*
+        * Fiemap callers may call for offset beyond s_bitmap_maxbytes.
+        * So handle it here itself instead of querying ext4_map_blocks().
+        * Since ext4_map_blocks() will warn about it and will return
+        * -EIO error.
+        */
+       if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
+               struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+               if (offset >= sbi->s_bitmap_maxbytes) {
+                       map.m_flags = 0;
+                       goto set_iomap;
+               }
+       }
+
        ret = ext4_map_blocks(NULL, inode, &map, 0);
        if (ret < 0)
                return ret;
        if (ret == 0)
                delalloc = ext4_iomap_is_delalloc(inode, &map);
 
+set_iomap:
        ext4_set_iomap(inode, iomap, &map, offset, length);
        if (delalloc && iomap->type == IOMAP_HOLE)
                iomap->type = IOMAP_DELALLOC;