[XFS] Increase the size of the buffer holding the local inode cluster

list, to increase our potential readahead window and in turn improve
bulkstat performance.

SGI-PV: 944409
SGI-Modid: xfs-linux-melb:xfs-kern:26607a

Signed-off-by: Nathan Scott <nathans@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>

1 files changed, 16 insertions, 6 deletions

diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index e6dbe6ba6fbd..315c9bcd3be3 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -324,6 +324,8 @@ xfs_bulkstat(
         xfs_agino_t             gino;   /* current btree rec's start inode */
         int                     i;      /* loop index */
         int                     icount; /* count of inodes good in irbuf */
+        int                     irbsize; /* size of irec buffer in bytes */
+        unsigned int            kmflags; /* flags for allocating irec buffer */
         xfs_ino_t               ino;    /* inode number (filesystem) */
         xfs_inobt_rec_incore_t  *irbp;  /* current irec buffer pointer */
         xfs_inobt_rec_incore_t  *irbuf; /* start of irec buffer */
@@ -369,12 +371,20 @@ xfs_bulkstat(
         nimask = ~(nicluster - 1);
         nbcluster = nicluster >> mp->m_sb.sb_inopblog;
         /*
-         * Allocate a page-sized buffer for inode btree records.
-         * We could try allocating something smaller, but for normal
-         * calls we'll always (potentially) need the whole page.
+         * Allocate a local buffer for inode cluster btree records.
+         * This caps our maximum readahead window (so don't be stingy)
+         * but we must handle the case where we can't get a contiguous
+         * multi-page buffer, so we drop back toward pagesize; the end
+         * case we ensure succeeds, via appropriate allocation flags.
          */
-        irbuf = kmem_alloc(NBPC, KM_SLEEP);
-        nirbuf = NBPC / sizeof(*irbuf);
+        irbsize = NBPP * 4;
+        kmflags = KM_SLEEP | KM_MAYFAIL;
+        while (!(irbuf = kmem_alloc(irbsize, kmflags))) {
+                if ((irbsize >>= 1) <= NBPP)
+                        kmflags = KM_SLEEP;
+        }
+        nirbuf = irbsize / sizeof(*irbuf);
+
         /*
          * Loop over the allocation groups, starting from the last
          * inode returned; 0 means start of the allocation group.
@@ -672,7 +682,7 @@ xfs_bulkstat(
         /*
          * Done, we're either out of filesystem or space to put the data.
          */
-        kmem_free(irbuf, NBPC);
+        kmem_free(irbuf, irbsize);
         *ubcountp = ubelem;
         if (agno >= mp->m_sb.sb_agcount) {
                 /*