linux-ext4 - [PATCH] e2fsprogs: Don't report uninit extents past EOF invalid

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Date:	Sun, 21 Jul 2013 16:28:49 -0400
From:	Eric Whitney <enwlinux@...il.com>
To:	linux-ext4@...r.kernel.org
Cc:	tytso@....edu
Subject: [PATCH] e2fsprogs: Don't report uninit extents past EOF invalid

Commit d3f32c2db8 caused e2fsck misbehavior during xfstests runs.
It reported that uninitialized extents created by fallocate() at
the end of file with the FALLOC_FL_KEEP_SIZE flag were invalid.
Because FALLOC_FL_KEEP_SIZE does not increase the file size when
an extent is fallocated, an uninitialized extent can legally contain
blocks past the end of file.

The information reported by ext2fs_extent_get() and used by the commit
to determine legal extent ranges is limited by the value of i_size
(determines end_blk in the root extent index), so block values greater
than that containing i_size were reported as invalid.

To fix this, filter out possible invalid extent candidates if they are
uninitialized and extend past the block containing the end of file.

Signed-off-by: Eric Whitney <enwlinux@...il.com>
---
 e2fsck/pass1.c      |    4 +++-
 lib/ext2fs/ext2fs.h |    1 +
 lib/ext2fs/extent.c |    1 +
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index ba6025b..b84b0d0 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -1892,7 +1892,9 @@ static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx,
 			problem = PR_1_EXTENT_BAD_START_BLK;
 		else if (extent.e_lblk < start_block)
 			problem = PR_1_OUT_OF_ORDER_EXTENTS;
-		else if (end_block && last_lblk > end_block)
+		else if ((end_block && last_lblk > end_block) &&
+			 (!(extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT &&
+			    last_lblk > info.eof_blk - 1)))
 			problem = PR_1_EXTENT_END_OUT_OF_BOUNDS;
 		else if (is_leaf && extent.e_len == 0)
 			problem = PR_1_EXTENT_LENGTH_ZERO;
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 311ceda..85f2ac8 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -409,6 +409,7 @@ struct ext2_extent_info {
 	int		bytes_avail;
 	blk64_t		max_lblk;
 	blk64_t		max_pblk;
+	blk64_t         eof_blk;
 	__u32		max_len;
 	__u32		max_uninit_len;
 };
diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c
index 65bb099..de54319 100644
--- a/lib/ext2fs/extent.c
+++ b/lib/ext2fs/extent.c
@@ -1572,6 +1572,7 @@ errcode_t ext2fs_extent_get_info(ext2_extent_handle_t handle,
 	info->max_depth = handle->max_depth;
 	info->max_lblk = ((__u64) 1 << 32) - 1;
 	info->max_pblk = ((__u64) 1 << 48) - 1;
+	info->eof_blk = handle->path[0].end_blk;
 	info->max_len = (1UL << 15);
 	info->max_uninit_len = (1UL << 15) - 1;
 
-- 
1.7.10.4

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