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Commit 50689696 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: make sure directory and symlink blocks are revoked 



When an inode gets unlinked, the functions ext4_clear_blocks() and
ext4_remove_blocks() call ext4_forget() for all the buffer heads
corresponding to the deleted inode's data blocks.  If the inode is a
directory or a symlink, the is_metadata parameter must be non-zero so
ext4_forget() will revoke them via jbd2_journal_revoke().  Otherwise,
if these blocks are reused for a data file, and the system crashes
before a journal checkpoint, the journal replay could end up
corrupting these data blocks.

Thanks to Curt Wohlgemuth for pointing out potential problems in this
area.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
parent beac2da7

fs/ext4/extents.c

+1 −1
Original line number Diff line number Diff line
@@ -2074,7 +2074,7 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode, 
		ext_debug("free last %u blocks starting %llu\n", num, start);

		for (i = 0; i < num; i++) {

			bh = sb_find_get_block(inode->i_sb, start + i);

			ext4_forget(handle, 0, inode, bh, start + i);

			ext4_forget(handle, metadata, inode, bh, start + i);

		}

		ext4_free_blocks(handle, inode, start, num, metadata);

	} else if (from == le32_to_cpu(ex->ee_block)

fs/ext4/inode.c

+4 −2
Original line number Diff line number Diff line
@@ -4121,6 +4121,8 @@ static void ext4_clear_blocks(handle_t *handle, struct inode *inode, 
			      __le32 *last)

{

	__le32 *p;

	int	is_metadata = S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode);



	if (try_to_extend_transaction(handle, inode)) {

		if (bh) {

			BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
@@ -4151,11 +4153,11 @@ static void ext4_clear_blocks(handle_t *handle, struct inode *inode, 


			*p = 0;

			tbh = sb_find_get_block(inode->i_sb, nr);

			ext4_forget(handle, 0, inode, tbh, nr);

			ext4_forget(handle, is_metadata, inode, tbh, nr);

		}

	}



	ext4_free_blocks(handle, inode, block_to_free, count, 0);

	ext4_free_blocks(handle, inode, block_to_free, count, is_metadata);

}



/**