Commit d62b1b87 authored by Chris Mason's avatar Chris Mason Committed by Linus Torvalds

[PATCH] resierfs: fix reiserfs_invalidatepage race against data=ordered

After a transaction has closed but before it has finished commit, there is
a window where data=ordered mode requires invalidatepage to pin pages
instead of freeing them.  This patch fixes a race between the
invalidatepage checks and data=ordered writeback, and it also adds a check
to the reiserfs write_ordered_buffers routines to write any anonymous
buffers that were dirtied after its first writeback loop.

That bug works like this:

proc1: transaction closes and a new one starts
proc1: write_ordered_buffers starts processing data=ordered list
proc1: buffer A is cleaned and written
proc2: buffer A is dirtied by another process
proc2: File is truncated to zero, page A goes through invalidatepage
proc2: reiserfs_invalidatepage sees dirty buffer A with reiserfs
       journal head, pins it
proc1: write_ordered_buffers frees the journal head on buffer A

At this point, buffer A stays dirty forever
Signed-off-by: default avatarChris Mason <mason@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ec191574
......@@ -2743,6 +2743,7 @@ static int invalidatepage_can_drop(struct inode *inode, struct buffer_head *bh)
int ret = 1;
struct reiserfs_journal *j = SB_JOURNAL(inode->i_sb);
lock_buffer(bh);
spin_lock(&j->j_dirty_buffers_lock);
if (!buffer_mapped(bh)) {
goto free_jh;
......@@ -2758,7 +2759,7 @@ static int invalidatepage_can_drop(struct inode *inode, struct buffer_head *bh)
if (buffer_journaled(bh) || buffer_journal_dirty(bh)) {
ret = 0;
}
} else if (buffer_dirty(bh) || buffer_locked(bh)) {
} else if (buffer_dirty(bh)) {
struct reiserfs_journal_list *jl;
struct reiserfs_jh *jh = bh->b_private;
......@@ -2784,6 +2785,7 @@ static int invalidatepage_can_drop(struct inode *inode, struct buffer_head *bh)
reiserfs_free_jh(bh);
}
spin_unlock(&j->j_dirty_buffers_lock);
unlock_buffer(bh);
return ret;
}
......
......@@ -877,6 +877,19 @@ static int write_ordered_buffers(spinlock_t * lock,
if (!buffer_uptodate(bh)) {
ret = -EIO;
}
/* ugly interaction with invalidatepage here.
* reiserfs_invalidate_page will pin any buffer that has a valid
* journal head from an older transaction. If someone else sets
* our buffer dirty after we write it in the first loop, and
* then someone truncates the page away, nobody will ever write
* the buffer. We're safe if we write the page one last time
* after freeing the journal header.
*/
if (buffer_dirty(bh) && unlikely(bh->b_page->mapping == NULL)) {
spin_unlock(lock);
ll_rw_block(WRITE, 1, &bh);
spin_lock(lock);
}
put_bh(bh);
cond_resched_lock(lock);
}
......
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