[PATCH 01/28] xfs: PF_FSTRANS should never be set in ->writepage

Christoph Hellwig
2011-07-07T11:06:43Z

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Now that we reject direct reclaim in addition to always using GFP_NOFS
allocation there's no chance we'll ever end up in ->writepage with
PF_FSTRANS set. Add a WARN_ON if we hit this case, and stop checking
if we'd actually need to start a transaction.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Index: xfs/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_aops.c 2011-07-06 09:11:58.963268764 +0200
+++ xfs/fs/xfs/linux-2.6/xfs_aops.c 2011-07-06 09:12:22.466600907 +0200
@@ -895,11 +895,6 @@ out_invalidate:
* For unwritten space on the page we need to start the conversion to
* regular allocated space.
* For any other dirty buffer heads on the page we should flush them.
- *
- * If we detect that a transaction would be required to flush the page, we
- * have to check the process flags first, if we are already in a transaction
- * or disk I/O during allocations is off, we need to fail the writepage and
- * redirty the page.
*/
STATIC int
xfs_vm_writepage(
@@ -907,7 +902,6 @@ xfs_vm_writepage(
struct writeback_control *wbc)
{
struct inode *inode = page->mapping->host;
- int delalloc, unwritten;
struct buffer_head *bh, *head;
struct xfs_bmbt_irec imap;
xfs_ioend_t *ioend = NULL, *iohead = NULL;
@@ -939,15 +933,10 @@ xfs_vm_writepage(
goto redirty;

/*
- * We need a transaction if there are delalloc or unwritten buffers
- * on the page.
- *
- * If we need a transaction and the process flags say we are already
- * in a transaction, or no IO is allowed then mark the page dirty
- * again and leave the page as is.
+ * Given that we do not allow direct reclaim to call us, we should
+ * never be called while in a filesystem transaction.
*/
- xfs_count_page_state(page, &delalloc, &unwritten);
- if ((current->flags & PF_FSTRANS) && (delalloc || unwritten))
+ if (WARN_ON(current->flags & PF_FSTRANS))
goto redirty;

/* Is this page beyond the end of the file? */