[XFS] write barrier support Issue all log sync operations as ordered

writes.  In addition flush the disk cache on fsync if the sync cached
operation didn't sync the log to disk (this requires some additional
bookeping in the transaction and log code). If the device doesn't claim to
support barriers, the filesystem has an extern log volume or the trial
superblock write with barriers enabled failed we disable barriers and
print a warning.  We should probably fail the mount completely, but that
could lead to nasty boot failures for the root filesystem.  Not enabled by
default yet, needs more destructive testing first.

SGI-PV: 912426
SGI-Modid: xfs-linux:xfs-kern:198723a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>

1 files changed, 37 insertions, 28 deletions

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 51814c32eddf..b9d3ad35240e 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -93,8 +93,11 @@ STATIC int  xlog_state_release_iclog(xlog_t		*log,
 STATIC void xlog_state_switch_iclogs(xlog_t             *log,
                                      xlog_in_core_t *iclog,
                                      int                eventual_size);
-STATIC int  xlog_state_sync(xlog_t *log, xfs_lsn_t lsn, uint flags);
-STATIC int  xlog_state_sync_all(xlog_t *log, uint flags);
+STATIC int  xlog_state_sync(xlog_t                      *log,
+                            xfs_lsn_t                   lsn,
+                            uint                        flags,
+                            int                         *log_flushed);
+STATIC int  xlog_state_sync_all(xlog_t *log, uint flags, int *log_flushed);
 STATIC void xlog_state_want_sync(xlog_t *log, xlog_in_core_t *iclog);
 
 /* local functions to manipulate grant head */
@@ -312,12 +315,17 @@ xfs_log_done(xfs_mount_t	*mp,
  * semaphore.
  */
 int
-xfs_log_force(xfs_mount_t *mp,
-              xfs_lsn_t   lsn,
-              uint        flags)
+_xfs_log_force(
+        xfs_mount_t     *mp,
+        xfs_lsn_t       lsn,
+        uint            flags,
+        int             *log_flushed)
 {
-        int     rval;
-        xlog_t *log = mp->m_log;
+        xlog_t          *log = mp->m_log;
+        int             dummy;
+
+        if (!log_flushed)
+                log_flushed = &dummy;
 
 #if defined(DEBUG) || defined(XLOG_NOLOG)
         if (!xlog_debug && xlog_target == log->l_targ)
@@ -328,17 +336,12 @@ xfs_log_force(xfs_mount_t *mp,
 
         XFS_STATS_INC(xs_log_force);
 
-        if ((log->l_flags & XLOG_IO_ERROR) == 0) {
-                if (lsn == 0)
-                        rval = xlog_state_sync_all(log, flags);
-                else
-                        rval = xlog_state_sync(log, lsn, flags);
-        } else {
-                rval = XFS_ERROR(EIO);
-        }
-
-        return rval;
-
+        if (log->l_flags & XLOG_IO_ERROR)
+                return XFS_ERROR(EIO);
+        if (lsn == 0)
+                return xlog_state_sync_all(log, flags, log_flushed);
+        else
+                return xlog_state_sync(log, lsn, flags, log_flushed);
 }       /* xfs_log_force */
 
 /*
@@ -1467,14 +1470,13 @@ xlog_sync(xlog_t		*log,
         XFS_BUF_BUSY(bp);
         XFS_BUF_ASYNC(bp);
         /*
-         * Do a disk write cache flush for the log block.
-         * This is a bit of a sledgehammer, it would be better
-         * to use a tag barrier here that just prevents reordering.
+         * Do an ordered write for the log block.
+         *
          * It may not be needed to flush the first split block in the log wrap
          * case, but do it anyways to be safe -AK
          */
-        if (!(log->l_mp->m_flags & XFS_MOUNT_NOLOGFLUSH))
-                XFS_BUF_FLUSH(bp);
+        if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)
+                XFS_BUF_ORDERED(bp);
 
         ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
         ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
@@ -1505,8 +1507,8 @@ xlog_sync(xlog_t		*log,
                 XFS_BUF_SET_FSPRIVATE(bp, iclog);
                 XFS_BUF_BUSY(bp);
                 XFS_BUF_ASYNC(bp);
-                if (!(log->l_mp->m_flags & XFS_MOUNT_NOLOGFLUSH))
-                        XFS_BUF_FLUSH(bp);
+                if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)
+                        XFS_BUF_ORDERED(bp);
                 dptr = XFS_BUF_PTR(bp);
                 /*
                  * Bump the cycle numbers at the start of each block
@@ -2951,7 +2953,7 @@ xlog_state_switch_iclogs(xlog_t		*log,
  *              not in the active nor dirty state.
  */
 STATIC int
-xlog_state_sync_all(xlog_t *log, uint flags)
+xlog_state_sync_all(xlog_t *log, uint flags, int *log_flushed)
 {
         xlog_in_core_t  *iclog;
         xfs_lsn_t       lsn;
@@ -3000,6 +3002,7 @@ xlog_state_sync_all(xlog_t *log, uint flags)
 
                                 if (xlog_state_release_iclog(log, iclog))
                                         return XFS_ERROR(EIO);
+                                *log_flushed = 1;
                                 s = LOG_LOCK(log);
                                 if (INT_GET(iclog->ic_header.h_lsn, ARCH_CONVERT) == lsn &&
                                     iclog->ic_state != XLOG_STATE_DIRTY)
@@ -3043,6 +3046,7 @@ maybe_sleep:
                  */
                 if (iclog->ic_state & XLOG_STATE_IOERROR)
                         return XFS_ERROR(EIO);
+                *log_flushed = 1;
 
         } else {
 
@@ -3068,7 +3072,8 @@ no_sleep:
 int
 xlog_state_sync(xlog_t    *log,
                 xfs_lsn_t lsn,
-                uint      flags)
+                uint      flags,
+                int       *log_flushed)
 {
     xlog_in_core_t      *iclog;
     int                 already_slept = 0;
@@ -3120,6 +3125,7 @@ try_again:
                         XFS_STATS_INC(xs_log_force_sleep);
                         sv_wait(&iclog->ic_prev->ic_writesema, PSWP,
                                 &log->l_icloglock, s);
+                        *log_flushed = 1;
                         already_slept = 1;
                         goto try_again;
                 } else {
@@ -3128,6 +3134,7 @@ try_again:
                         LOG_UNLOCK(log, s);
                         if (xlog_state_release_iclog(log, iclog))
                                 return XFS_ERROR(EIO);
+                        *log_flushed = 1;
                         s = LOG_LOCK(log);
                 }
         }
@@ -3152,6 +3159,7 @@ try_again:
                  */
                 if (iclog->ic_state & XLOG_STATE_IOERROR)
                         return XFS_ERROR(EIO);
+                *log_flushed = 1;
         } else {                /* just return */
                 LOG_UNLOCK(log, s);
         }
@@ -3606,6 +3614,7 @@ xfs_log_force_umount(
         xlog_ticket_t   *tic;
         xlog_t          *log;
         int             retval;
+        int             dummy;
         SPLDECL(s);
         SPLDECL(s2);
 
@@ -3684,7 +3693,7 @@ xfs_log_force_umount(
                  * Force the incore logs to disk before shutting the
                  * log down completely.
                  */
-                xlog_state_sync_all(log, XFS_LOG_FORCE|XFS_LOG_SYNC);
+                xlog_state_sync_all(log, XFS_LOG_FORCE|XFS_LOG_SYNC, &dummy);
                 s2 = LOG_LOCK(log);
                 retval = xlog_state_ioerror(log);
                 LOG_UNLOCK(log, s2);