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Commit e6b5d301 authored Jul 13, 2009 by Curt Wohlgemuth Committed by Theodore Ts'o Jul 13, 2009

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: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

parent 62e086be

fs/ext4/ext4_jbd2.c

+4 −0

Original line number	Original line	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,		ext4_journal_abort_handle(where, __func__, bh,
	handle, err);		handle, err);
	}		}
			else
			brelse(bh);
	return err;		return err;
	}		}

	@@ -57,6 +59,8 @@ int __ext4_journal_revoke(const char where, handle_t handle,
	ext4_journal_abort_handle(where, __func__, bh,		ext4_journal_abort_handle(where, __func__, bh,
	handle, err);		handle, err);
	}		}
			else
			brelse(bh);
	return err;		return err;
	}		}

fs/ext4/ext4_jbd2.h

+2 −0

Original line number	Original line	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,		int __ext4_journal_get_write_access(const char where, handle_t handle,
	struct buffer_head *bh);		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,		int __ext4_journal_forget(const char where, handle_t handle,
	struct buffer_head *bh);		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,		int __ext4_journal_revoke(const char where, handle_t handle,
	ext4_fsblk_t blocknr, struct buffer_head *bh);		ext4_fsblk_t blocknr, struct buffer_head *bh);

fs/ext4/inode.c

+2 −4

Original line number	Original line	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		* but there may still be a record of it in the journal, and that record
	* still needs to be revoked.		* 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,		int ext4_forget(handle_t handle, int is_metadata, struct inode inode,
	struct buffer_head *bh, ext4_fsblk_t blocknr)		struct buffer_head *bh, ext4_fsblk_t blocknr)
	{		{
	int err;		int err;

	if (!ext4_handle_valid(handle))
	return 0;

	might_sleep();		might_sleep();

	BUFFER_TRACE(bh, "enter");		BUFFER_TRACE(bh, "enter");