Commit 801674f3 authored Mar 31, 2020 by Jan Kara Committed by Theodore Ts'o Apr 15, 2020

ext4: do not zeroout extents beyond i_disksize



We do not want to create initialized extents beyond end of file because
for e2fsck it is impossible to distinguish them from a case of corrupted
file size / extent tree and so it complains like:

Inode 12, i_size is 147456, should be 163840.  Fix? no

Code in ext4_ext_convert_to_initialized() and
ext4_split_convert_extents() try to make sure it does not create
initialized extents beyond inode size however they check against
inode->i_size which is wrong. They should instead check against
EXT4_I(inode)->i_disksize which is the current inode size on disk.
That's what e2fsck is going to see in case of crash before all dirty
data is written. This bug manifests as generic/456 test failure (with
recent enough fstests where fsx got fixed to properly pass
FALLOC_KEEP_SIZE_FL flags to the kernel) when run with dioread_lock
mount option.

CC: stable@vger.kernel.org
Fixes: 21ca087a ("ext4: Do not zero out uninitialized extents beyond i_size")
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20200331105016.8674-1-jack@suse.cz


Signed-off-by: Theodore Ts'o <tytso@mit.edu>

parent 9033783c

fs/ext4/extents.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -3374,8 +3374,8 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
		(unsigned long long)map->m_lblk, map_len);

		sbi = EXT4_SB(inode->i_sb);
		eof_block = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
		inode->i_sb->s_blocksize_bits;
		eof_block = (EXT4_I(inode)->i_disksize + inode->i_sb->s_blocksize - 1)
		>> inode->i_sb->s_blocksize_bits;
		if (eof_block < map->m_lblk + map_len)
		eof_block = map->m_lblk + map_len;

		@@ -3627,8 +3627,8 @@ static int ext4_split_convert_extents(handle_t *handle,
		__func__, inode->i_ino,
		(unsigned long long)map->m_lblk, map->m_len);

		eof_block = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
		inode->i_sb->s_blocksize_bits;
		eof_block = (EXT4_I(inode)->i_disksize + inode->i_sb->s_blocksize - 1)
		>> inode->i_sb->s_blocksize_bits;
		if (eof_block < map->m_lblk + map->m_len)
		eof_block = map->m_lblk + map->m_len;
		/*

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