[XFS] Convert l_flushsema to a sv_t

The l_flushsema doesn't exactly have completion semantics, nor mutex
semantics. It's used as a list of tasks which are waiting to be notified
that a flush has completed. It was also being used in a way that was
potentially racy, depending on the semaphore implementation.

By using a sv_t instead of a semaphore we avoid the need for a separate
counter, since we know we just need to wake everything on the queue.

Original waitqueue implementation from Matthew Wilcox. Cleanup and
conversion to sv_t by Christoph Hellwig.

SGI-PV: 981507
SGI-Modid: xfs-linux-melb:xfs-kern:31059a

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 8952a392b5f3..6245913196b4 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -423,10 +423,8 @@ typedef struct log {
         int                     l_logBBsize;    /* size of log in BB chunks */
 
         /* The following block of fields are changed while holding icloglock */
-        sema_t                  l_flushsema ____cacheline_aligned_in_smp;
-                                                /* iclog flushing semaphore */
-        int                     l_flushcnt;     /* # of procs waiting on this
-                                                 * sema */
+        sv_t                    l_flush_wait ____cacheline_aligned_in_smp;
+                                                /* waiting for iclog flush */
         int                     l_covered_state;/* state of "covering disk
                                                  * log entries" */
         xlog_in_core_t          *l_iclog;       /* head log queue       */