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

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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>
This commit is contained in:
Curt Wohlgemuth 2009-07-13 09:07:20 -04:00 committed by Theodore Ts'o
parent 62e086be5d
commit e6b5d30104
3 changed files with 8 additions and 4 deletions
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4
fs/ext4/ext4_jbd2.c
View file

@ -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;
}

2
fs/ext4/ext4_jbd2.h
View file

@ -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);

6
fs/ext4/inode.c
View file

@ -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");