On 2/26/20 9:41 PM, Darrick J. Wong wrote:
On Wed, Feb 26, 2020 at 03:27:06PM +0530, Ritesh Harjani wrote:
For indirect block mapping if the i_block > max supported block in inode
then ext4_ind_map_blocks may return a -EIO error. But in case of fiemap
this could be a valid query to ext4_map_blocks.
So in case if !create then return 0. This also makes ext4_warning to
ext4_debug in ext4_block_to_path() for the same reason.
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
---
fs/ext4/indirect.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 3a4ab70fe9e0..e1ab495dd900 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -102,7 +102,11 @@ static int ext4_block_to_path(struct inode *inode,
offsets[n++] = i_block & (ptrs - 1);
final = ptrs;
} else {
- ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
+ /*
+ * It's not yet an error to just query beyond max
+ * block in inode. Fiemap callers may do so.
+ */
+ ext4_debug("block %lu > max in inode %lu",
i_block + direct_blocks +
indirect_blocks + double_blocks, inode->i_ino);
Does that mean fiemap callers can spamflood dmesg with this message just
by setting the query start range to a huge value?
Not in the old implementation. But This could happen with indirect
block mapping with new implementation in iomap (as there is no check in
place before calling ext4_map_blocks()).
Previously __generic_block_fiemap() used to not query beyond
i_size_read(), so we were safe there.
So yes now as Jan also suggested, will add a check in place in
ext4_iomap_begin_report() itself, so that this flooding wont happen.
Thanks for the review!!
-ritesh
--D
}
@@ -537,8 +541,11 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
depth = ext4_block_to_path(inode, map->m_lblk, offsets,
&blocks_to_boundary);
- if (depth == 0)
+ if (depth == 0) {
+ if (!(flags & EXT4_GET_BLOCKS_CREATE))
+ err = 0;
goto out;
+ }
partial = ext4_get_branch(inode, depth, offsets, chain, &err);
--
2.21.0
