Commit e6b5d301 authored by Curt Wohlgemuth's avatar Curt Wohlgemuth Committed by Theodore Ts'o
Browse files

ext4: Fix buffer head reference leak in no-journal mode 



We found a problem with buffer head reference leaks when using an ext4
partition without a journal.  In particular, calls to ext4_forget() would
not to a brelse() on the input buffer head, which will cause pages they
belong to to not be reclaimable.

Further investigation showed that all places where ext4_journal_forget() and
ext4_journal_revoke() are called are subject to the same problem.  The patch
below changes __ext4_journal_forget/__ext4_journal_revoke to do an explicit
release of the buffer head when the journal handle isn't valid.

Signed-off-by: default avatarCurt Wohlgemuth <curtw@google.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 62e086be

fs/ext4/ext4_jbd2.c

+4 −0
Original line number Diff line number Diff line
@@ -43,6 +43,8 @@ int __ext4_journal_forget(const char *where, handle_t *handle, 
			ext4_journal_abort_handle(where, __func__, bh,

						  handle, err);

	}

	else

		brelse(bh);

	return err;

}
@@ -57,6 +59,8 @@ int __ext4_journal_revoke(const char *where, handle_t *handle, 
			ext4_journal_abort_handle(where, __func__, bh,

						  handle, err);

	}

	else

		brelse(bh);

	return err;

}

fs/ext4/ext4_jbd2.h

+2 −0
Original line number Diff line number Diff line
@@ -131,9 +131,11 @@ int __ext4_journal_get_undo_access(const char *where, handle_t *handle, 
int __ext4_journal_get_write_access(const char *where, handle_t *handle,

				struct buffer_head *bh);



/* When called with an invalid handle, this will still do a put on the BH */

int __ext4_journal_forget(const char *where, handle_t *handle,

				struct buffer_head *bh);



/* When called with an invalid handle, this will still do a put on the BH */

int __ext4_journal_revoke(const char *where, handle_t *handle,

				ext4_fsblk_t blocknr, struct buffer_head *bh);

fs/ext4/inode.c

+2 −4
Original line number Diff line number Diff line
@@ -78,16 +78,14 @@ static int ext4_inode_is_fast_symlink(struct inode *inode) 
 * but there may still be a record of it in the journal, and that record

 * still needs to be revoked.

 *

 * If the handle isn't valid we're not journaling so there's nothing to do.

 * If the handle isn't valid we're not journaling, but we still need to

 * call into ext4_journal_revoke() to put the buffer head.

 */

int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,

		struct buffer_head *bh, ext4_fsblk_t blocknr)

{

	int err;



	if (!ext4_handle_valid(handle))

		return 0;



	might_sleep();



	BUFFER_TRACE(bh, "enter");

CRA Git | Maintained and supported by SUSTech CRA and CCSE