public inbox for linux-xfs@vger.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@infradead.org>
To: xfs@oss.sgi.com
Cc: Thomas Neumann <tneumann@users.sourceforge.net>
Subject: [PATCH] xfs: I/O completion handlers must use NOFS allocations
Date: Mon, 19 Oct 2009 00:00:03 -0400	[thread overview]
Message-ID: <20091019040003.GA21115@infradead.org> (raw)

When complention I/O requests we must not allow the memory allocator to
recurse into the filesystem, as we might deadlock on waiting for the
I/O completion otherwise.  The only thing currently allocting normal
GFP_KERNEL memory is the allocation of the transaction structure for the
unwritten extent conversion.  Add a memflags argument to _xfs_trans_alloc
to allow controlling the allocator behaviour.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Thomas Neumann <tneumann@users.sourceforge.net>
Tested-by: Thomas Neumann <tneumann@users.sourceforge.net>

Index: linux-2.6/fs/xfs/xfs_fsops.c
===================================================================
--- linux-2.6.orig/fs/xfs/xfs_fsops.c	2009-10-16 23:08:25.170027882 +0200
+++ linux-2.6/fs/xfs/xfs_fsops.c	2009-10-16 23:09:22.904256700 +0200
@@ -611,7 +611,7 @@ xfs_fs_log_dummy(
 	xfs_inode_t	*ip;
 	int		error;
 
-	tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
+	tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
 	error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0);
 	if (error) {
 		xfs_trans_cancel(tp, 0);
Index: linux-2.6/fs/xfs/xfs_iomap.c
===================================================================
--- linux-2.6.orig/fs/xfs/xfs_iomap.c	2009-10-16 23:10:14.342278346 +0200
+++ linux-2.6/fs/xfs/xfs_iomap.c	2009-10-16 23:12:08.148004392 +0200
@@ -860,8 +860,15 @@ xfs_iomap_write_unwritten(
 		 * set up a transaction to convert the range of extents
 		 * from unwritten to real. Do allocations in a loop until
 		 * we have covered the range passed in.
+		 *
+		 * Note that we opencoding the transaction allocation here
+		 * to pass KM_NOFS - we can't risk to recurse back into
+		 * the filesystem here as we might be asked to write out
+		 * the same inode that we complete here and might deadlock
+		 * on the iolock.
 		 */
-		tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
+		xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
+		tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
 		tp->t_flags |= XFS_TRANS_RESERVE;
 		error = xfs_trans_reserve(tp, resblks,
 				XFS_WRITE_LOG_RES(mp), 0,
Index: linux-2.6/fs/xfs/xfs_mount.c
===================================================================
--- linux-2.6.orig/fs/xfs/xfs_mount.c	2009-10-16 23:08:25.147024815 +0200
+++ linux-2.6/fs/xfs/xfs_mount.c	2009-10-16 23:09:25.127005437 +0200
@@ -1471,7 +1471,7 @@ xfs_log_sbcount(
 	if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
 		return 0;
 
-	tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT);
+	tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP);
 	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
 					XFS_DEFAULT_LOG_COUNT);
 	if (error) {
Index: linux-2.6/fs/xfs/xfs_trans.c
===================================================================
--- linux-2.6.orig/fs/xfs/xfs_trans.c	2009-10-16 23:08:25.117003816 +0200
+++ linux-2.6/fs/xfs/xfs_trans.c	2009-10-16 23:08:58.202005942 +0200
@@ -236,19 +236,20 @@ xfs_trans_alloc(
 	uint		type)
 {
 	xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
-	return _xfs_trans_alloc(mp, type);
+	return _xfs_trans_alloc(mp, type, KM_SLEEP);
 }
 
 xfs_trans_t *
 _xfs_trans_alloc(
 	xfs_mount_t	*mp,
-	uint		type)
+	uint		type,
+	uint		memflags)
 {
 	xfs_trans_t	*tp;
 
 	atomic_inc(&mp->m_active_trans);
 
-	tp = kmem_zone_zalloc(xfs_trans_zone, KM_SLEEP);
+	tp = kmem_zone_zalloc(xfs_trans_zone, memflags);
 	tp->t_magic = XFS_TRANS_MAGIC;
 	tp->t_type = type;
 	tp->t_mountp = mp;
Index: linux-2.6/fs/xfs/xfs_trans.h
===================================================================
--- linux-2.6.orig/fs/xfs/xfs_trans.h	2009-10-16 23:08:25.127003692 +0200
+++ linux-2.6/fs/xfs/xfs_trans.h	2009-10-16 23:09:04.726256000 +0200
@@ -924,7 +924,7 @@ typedef struct xfs_trans {
  * XFS transaction mechanism exported interfaces.
  */
 xfs_trans_t	*xfs_trans_alloc(struct xfs_mount *, uint);
-xfs_trans_t	*_xfs_trans_alloc(struct xfs_mount *, uint);
+xfs_trans_t	*_xfs_trans_alloc(struct xfs_mount *, uint, uint);
 xfs_trans_t	*xfs_trans_dup(xfs_trans_t *);
 int		xfs_trans_reserve(xfs_trans_t *, uint, uint, uint,
 				  uint, uint);

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

             reply	other threads:[~2009-10-19  3:58 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-19  4:00 Christoph Hellwig [this message]
2009-10-30  8:55 ` [PATCH] xfs: I/O completion handlers must use NOFS allocations Christoph Hellwig
2009-11-02 20:34 ` Alex Elder
2009-11-03 14:45   ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20091019040003.GA21115@infradead.org \
    --to=hch@infradead.org \
    --cc=tneumann@users.sourceforge.net \
    --cc=xfs@oss.sgi.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox