Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6

* 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6: (87 commits)
  [XFS] Fix merge failure
  [XFS] The forward declarations for the xfs_ioctl() helpers and the
  [XFS] Update XFS documentation for noikeep/ikeep.
  [XFS] Update XFS Documentation for ikeep and ihashsize
  [XFS] Remove unused HAVE_SPLICE macro.
  [XFS] Remove CONFIG_XFS_SECURITY.
  [XFS] xfs_bmap_compute_maxlevels should be based on di_forkoff
  [XFS] Always use di_forkoff when checking for attr space.
  [XFS] Ensure the inode is joined in xfs_itruncate_finish
  [XFS] Remove periodic logging of in-core superblock counters.
  [XFS] fix logic error in xfs_alloc_ag_vextent_near()
  [XFS] Don't error out on good I/Os.
  [XFS] Catch log unmount failures.
  [XFS] Sanitise xfs_log_force error checking.
  [XFS] Check for errors when changing buffer pointers.
  [XFS] Don't allow silent errors in xfs_inactive().
  [XFS] Catch errors from xfs_imap().
  [XFS] xfs_bulkstat_one_dinode() never returns an error.
  [XFS] xfs_iflush_fork() never returns an error.
  [XFS] Catch unwritten extent conversion errors.
  ...

2 files changed, 21 insertions, 19 deletions

diff --git a/fs/xfs/support/ktrace.c b/fs/xfs/support/ktrace.c
index 129067cfcb86..0b75d302508f 100644
--- a/fs/xfs/support/ktrace.c
+++ b/fs/xfs/support/ktrace.c
@@ -24,7 +24,7 @@ static int          ktrace_zentries;
 void __init
 ktrace_init(int zentries)
 {
-        ktrace_zentries = zentries;
+        ktrace_zentries = roundup_pow_of_two(zentries);
 
         ktrace_hdr_zone = kmem_zone_init(sizeof(ktrace_t),
                                         "ktrace_hdr");
@@ -47,13 +47,16 @@ ktrace_uninit(void)
  * ktrace_alloc()
  *
  * Allocate a ktrace header and enough buffering for the given
- * number of entries.
+ * number of entries. Round the number of entries up to a
+ * power of 2 so we can do fast masking to get the index from
+ * the atomic index counter.
  */
 ktrace_t *
 ktrace_alloc(int nentries, unsigned int __nocast sleep)
 {
         ktrace_t        *ktp;
         ktrace_entry_t  *ktep;
+        int             entries;
 
         ktp = (ktrace_t*)kmem_zone_alloc(ktrace_hdr_zone, sleep);
 
@@ -70,11 +73,12 @@ ktrace_alloc(int nentries, unsigned int __nocast sleep)
         /*
          * Special treatment for buffers with the ktrace_zentries entries
          */
-        if (nentries == ktrace_zentries) {
+        entries = roundup_pow_of_two(nentries);
+        if (entries == ktrace_zentries) {
                 ktep = (ktrace_entry_t*)kmem_zone_zalloc(ktrace_ent_zone,
                                                             sleep);
         } else {
-                ktep = (ktrace_entry_t*)kmem_zalloc((nentries * sizeof(*ktep)),
+                ktep = (ktrace_entry_t*)kmem_zalloc((entries * sizeof(*ktep)),
                                                             sleep | KM_LARGE);
         }
 
@@ -91,8 +95,10 @@ ktrace_alloc(int nentries, unsigned int __nocast sleep)
         }
 
         ktp->kt_entries  = ktep;
-        ktp->kt_nentries = nentries;
-        ktp->kt_index    = 0;
+        ktp->kt_nentries = entries;
+        ASSERT(is_power_of_2(entries));
+        ktp->kt_index_mask = entries - 1;
+        atomic_set(&ktp->kt_index, 0);
         ktp->kt_rollover = 0;
         return ktp;
 }
@@ -151,8 +157,6 @@ ktrace_enter(
         void            *val14,
         void            *val15)
 {
-        static DEFINE_SPINLOCK(wrap_lock);
-        unsigned long   flags;
         int             index;
         ktrace_entry_t  *ktep;
 
@@ -161,12 +165,8 @@ ktrace_enter(
         /*
          * Grab an entry by pushing the index up to the next one.
          */
-        spin_lock_irqsave(&wrap_lock, flags);
-        index = ktp->kt_index;
-        if (++ktp->kt_index == ktp->kt_nentries)
-                ktp->kt_index = 0;
-        spin_unlock_irqrestore(&wrap_lock, flags);
-
+        index = atomic_add_return(1, &ktp->kt_index);
+        index = (index - 1) & ktp->kt_index_mask;
         if (!ktp->kt_rollover && index == ktp->kt_nentries - 1)
                 ktp->kt_rollover = 1;
 
@@ -199,11 +199,12 @@ int
 ktrace_nentries(
         ktrace_t        *ktp)
 {
-        if (ktp == NULL) {
+        int     index;
+        if (ktp == NULL)
                 return 0;
-        }
 
-        return (ktp->kt_rollover ? ktp->kt_nentries : ktp->kt_index);
+        index = atomic_read(&ktp->kt_index) & ktp->kt_index_mask;
+        return (ktp->kt_rollover ? ktp->kt_nentries : index);
 }
 
 /*
@@ -228,7 +229,7 @@ ktrace_first(ktrace_t   *ktp, ktrace_snap_t     *ktsp)
         int             nentries;
 
         if (ktp->kt_rollover)
-                index = ktp->kt_index;
+                index = atomic_read(&ktp->kt_index) & ktp->kt_index_mask;
         else
                 index = 0;
 
diff --git a/fs/xfs/support/ktrace.h b/fs/xfs/support/ktrace.h
index 56e72b40a859..741d6947ca60 100644
--- a/fs/xfs/support/ktrace.h
+++ b/fs/xfs/support/ktrace.h
@@ -30,7 +30,8 @@ typedef struct ktrace_entry {
  */
 typedef struct ktrace {
         int             kt_nentries;    /* number of entries in trace buf */
-        int             kt_index;       /* current index in entries */
+        atomic_t        kt_index;       /* current index in entries */
+        unsigned int    kt_index_mask;
         int             kt_rollover;
         ktrace_entry_t  *kt_entries;    /* buffer of entries */
 } ktrace_t;