linux-ext4 - [PATCHv3 4/6] ext4: Make ext4_ind_map

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Date:   Wed, 26 Feb 2020 15:27:06 +0530
From:   Ritesh Harjani <riteshh@...ux.ibm.com>
To:     jack@...e.cz, tytso@....edu, linux-ext4@...r.kernel.org
Cc:     adilger.kernel@...ger.ca, linux-fsdevel@...r.kernel.org,
        darrick.wong@...cle.com, hch@...radead.org, cmaiolino@...hat.com,
        Ritesh Harjani <riteshh@...ux.ibm.com>
Subject: [PATCHv3 4/6] 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 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@...ux.ibm.com>
---
 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);
 	}
@@ -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