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[PATCH 31/34] xfs: convert log grant heads to atomic variables

To: xfs@xxxxxxxxxxx
Subject: [PATCH 31/34] xfs: convert log grant heads to atomic variables
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 21 Dec 2010 18:29:27 +1100
In-reply-to: <1292916570-25015-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1292916570-25015-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

Convert the log grant heads to atomic64_t types in preparation for
converting the accounting algorithms to atomic operations. his patch
just converts the variables; the algorithmic changes are in a
separate patch for clarity.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/xfs_log.c      |    8 ++++----
 fs/xfs/xfs_log_priv.h |   12 ++++++------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index d118bf8..a1d7d12 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -47,7 +47,7 @@ STATIC xlog_t *  xlog_alloc_log(xfs_mount_t   *mp,
                                xfs_buftarg_t   *log_target,
                                xfs_daddr_t     blk_offset,
                                int             num_bblks);
-STATIC int      xlog_space_left(struct log *log, int64_t *head);
+STATIC int      xlog_space_left(struct log *log, atomic64_t *head);
 STATIC int      xlog_sync(xlog_t *log, xlog_in_core_t *iclog);
 STATIC void     xlog_dealloc_log(xlog_t *log);
 
@@ -100,7 +100,7 @@ STATIC int  xlog_iclogs_empty(xlog_t *log);
 static void
 xlog_grant_sub_space(
        struct log      *log,
-       int64_t         *head,
+       atomic64_t      *head,
        int             bytes)
 {
        int             cycle, space;
@@ -119,7 +119,7 @@ xlog_grant_sub_space(
 static void
 xlog_grant_add_space(
        struct log      *log,
-       int64_t         *head,
+       atomic64_t      *head,
        int             bytes)
 {
        int             tmp;
@@ -816,7 +816,7 @@ xlog_assign_tail_lsn(
 STATIC int
 xlog_space_left(
        struct log      *log,
-       int64_t         *head)
+       atomic64_t      *head)
 {
        int             free_bytes;
        int             tail_bytes;
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index d34af1c..7619d6a 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -514,8 +514,8 @@ typedef struct log {
        spinlock_t              l_grant_lock ____cacheline_aligned_in_smp;
        struct list_head        l_reserveq;
        struct list_head        l_writeq;
-       int64_t                 l_grant_reserve_head;
-       int64_t                 l_grant_write_head;
+       atomic64_t                      l_grant_reserve_head;
+       atomic64_t                      l_grant_write_head;
 
        /*
         * l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
@@ -596,18 +596,18 @@ xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint 
block)
  * will always get consistent component values to work from.
  */
 static inline void
-xlog_crack_grant_head(int64_t *head, int *cycle, int *space)
+xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space)
 {
-       int64_t val = *head;
+       int64_t val = atomic64_read(head);
 
        *cycle = val >> 32;
        *space = val & 0xffffffff;
 }
 
 static inline void
-xlog_assign_grant_head(int64_t *head, int cycle, int space)
+xlog_assign_grant_head(atomic64_t *head, int cycle, int space)
 {
-       *head = ((int64_t)cycle << 32) | space;
+       atomic64_set(head, ((int64_t)cycle << 32) | space);
 }
 
 /*
-- 
1.7.2.3

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