8 files changed, 86 insertions, 90 deletions

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index 84070f2e0ba4..4d66bb75579c 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -2276,7 +2276,6 @@ xfs_alloc_vextent(
                  * These three force us into a single a.g.
                  */
                 args->agno = XFS_FSB_TO_AGNO(mp, args->fsbno);
-                down_read(&mp->m_peraglock);
                 args->pag = xfs_perag_get(mp, args->agno);
                 args->minleft = 0;
                 error = xfs_alloc_fix_freelist(args, 0);
@@ -2286,14 +2285,12 @@ xfs_alloc_vextent(
                         goto error0;
                 }
                 if (!args->agbp) {
-                        up_read(&mp->m_peraglock);
                         trace_xfs_alloc_vextent_noagbp(args);
                         break;
                 }
                 args->agbno = XFS_FSB_TO_AGBNO(mp, args->fsbno);
                 if ((error = xfs_alloc_ag_vextent(args)))
                         goto error0;
-                up_read(&mp->m_peraglock);
                 break;
         case XFS_ALLOCTYPE_START_BNO:
                 /*
@@ -2345,7 +2342,6 @@ xfs_alloc_vextent(
                  * Loop over allocation groups twice; first time with
                  * trylock set, second time without.
                  */
-                down_read(&mp->m_peraglock);
                 for (;;) {
                         args->pag = xfs_perag_get(mp, args->agno);
                         if (no_min) args->minleft = 0;
@@ -2408,7 +2404,6 @@ xfs_alloc_vextent(
                         }
                         xfs_perag_put(args->pag);
                 }
-                up_read(&mp->m_peraglock);
                 if (bump_rotor || (type == XFS_ALLOCTYPE_ANY_AG)) {
                         if (args->agno == sagno)
                                 mp->m_agfrotor = (mp->m_agfrotor + 1) %
@@ -2438,7 +2433,6 @@ xfs_alloc_vextent(
         return 0;
 error0:
         xfs_perag_put(args->pag);
-        up_read(&mp->m_peraglock);
         return error;
 }
 
@@ -2463,7 +2457,6 @@ xfs_free_extent(
         args.agno = XFS_FSB_TO_AGNO(args.mp, bno);
         ASSERT(args.agno < args.mp->m_sb.sb_agcount);
         args.agbno = XFS_FSB_TO_AGBNO(args.mp, bno);
-        down_read(&args.mp->m_peraglock);
         args.pag = xfs_perag_get(args.mp, args.agno);
         if ((error = xfs_alloc_fix_freelist(&args, XFS_ALLOC_FLAG_FREEING)))
                 goto error0;
@@ -2475,7 +2468,6 @@ xfs_free_extent(
         error = xfs_free_ag_extent(tp, args.agbp, args.agno, args.agbno, len, 0);
 error0:
         xfs_perag_put(args.pag);
-        up_read(&args.mp->m_peraglock);
         return error;
 }
 
diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index a9b95d9cf2ad..7c6d9acd7154 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -2629,14 +2629,12 @@ xfs_bmap_btalloc(
                 if (startag == NULLAGNUMBER)
                         startag = ag = 0;
                 notinit = 0;
-                down_read(&mp->m_peraglock);
                 pag = xfs_perag_get(mp, ag);
                 while (blen < ap->alen) {
                         if (!pag->pagf_init &&
                             (error = xfs_alloc_pagf_init(mp, args.tp,
                                     ag, XFS_ALLOC_FLAG_TRYLOCK))) {
                                 xfs_perag_put(pag);
-                                up_read(&mp->m_peraglock);
                                 return error;
                         }
                         /*
@@ -2669,10 +2667,8 @@ xfs_bmap_btalloc(
 
                                         error = xfs_filestream_new_ag(ap, &ag);
                                         xfs_perag_put(pag);
-                                        if (error) {
-                                                up_read(&mp->m_peraglock);
+                                        if (error)
                                                 return error;
-                                        }
 
                                         /* loop again to set 'blen'*/
                                         startag = NULLAGNUMBER;
@@ -2688,7 +2684,6 @@ xfs_bmap_btalloc(
                         pag = xfs_perag_get(mp, ag);
                 }
                 xfs_perag_put(pag);
-                up_read(&mp->m_peraglock);
                 /*
                  * Since the above loop did a BUF_TRYLOCK, it is
                  * possible that there is space for this request.
diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
index e61f2aa088a9..914d00d0f119 100644
--- a/fs/xfs/xfs_filestream.c
+++ b/fs/xfs/xfs_filestream.c
@@ -253,8 +253,7 @@ next_ag:
 
 /*
  * Set the allocation group number for a file or a directory, updating inode
- * references and per-AG references as appropriate.  Must be called with the
- * m_peraglock held in read mode.
+ * references and per-AG references as appropriate.
  */
 static int
 _xfs_filestream_update_ag(
@@ -456,10 +455,10 @@ xfs_filestream_unmount(
 }
 
 /*
- * If the mount point's m_perag array is going to be reallocated, all
+ * If the mount point's m_perag tree is going to be modified, all
  * outstanding cache entries must be flushed to avoid accessing reference count
  * addresses that have been freed.  The call to xfs_filestream_flush() must be
- * made inside the block that holds the m_peraglock in write mode to do the
+ * made inside the block that holds the m_perag_lock in write mode to do the
  * reallocation.
  */
 void
@@ -531,7 +530,6 @@ xfs_filestream_associate(
 
         mp = pip->i_mount;
         cache = mp->m_filestream;
-        down_read(&mp->m_peraglock);
 
         /*
          * We have a problem, Houston.
@@ -548,10 +546,8 @@ xfs_filestream_associate(
          *
          * So, if we can't get the iolock without sleeping then just give up
          */
-        if (!xfs_ilock_nowait(pip, XFS_IOLOCK_EXCL)) {
-                up_read(&mp->m_peraglock);
+        if (!xfs_ilock_nowait(pip, XFS_IOLOCK_EXCL))
                 return 1;
-        }
 
         /* If the parent directory is already in the cache, use its AG. */
         item = xfs_mru_cache_lookup(cache, pip->i_ino);
@@ -606,7 +602,6 @@ exit_did_pick:
 
 exit:
         xfs_iunlock(pip, XFS_IOLOCK_EXCL);
-        up_read(&mp->m_peraglock);
         return -err;
 }
 
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index a13919a6a364..37a6f62c57b6 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -167,27 +167,14 @@ xfs_growfs_data_private(
         }
         new = nb - mp->m_sb.sb_dblocks;
         oagcount = mp->m_sb.sb_agcount;
-        if (nagcount > oagcount) {
-                void *new_perag, *old_perag;
-
-                xfs_filestream_flush(mp);
-
-                new_perag = kmem_zalloc(sizeof(xfs_perag_t) * nagcount,
-                                        KM_MAYFAIL);
-                if (!new_perag)
-                        return XFS_ERROR(ENOMEM);
-
-                down_write(&mp->m_peraglock);
-                memcpy(new_perag, mp->m_perag, sizeof(xfs_perag_t) * oagcount);
-                old_perag = mp->m_perag;
-                mp->m_perag = new_perag;
-
-                mp->m_flags |= XFS_MOUNT_32BITINODES;
-                nagimax = xfs_initialize_perag(mp, nagcount);
-                up_write(&mp->m_peraglock);
 
-                kmem_free(old_perag);
+        /* allocate the new per-ag structures */
+        if (nagcount > oagcount) {
+                error = xfs_initialize_perag(mp, nagcount, &nagimax);
+                if (error)
+                        return error;
         }
+
         tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFS);
         tp->t_flags |= XFS_TRANS_RESERVE;
         if ((error = xfs_trans_reserve(tp, XFS_GROWFS_SPACE_RES(mp),
@@ -196,6 +183,11 @@ xfs_growfs_data_private(
                 return error;
         }
 
+        /*
+         * Write new AG headers to disk. Non-transactional, but written
+         * synchronously so they are completed prior to the growfs transaction
+         * being logged.
+         */
         nfree = 0;
         for (agno = nagcount - 1; agno >= oagcount; agno--, new -= agsize) {
                 /*
@@ -359,6 +351,12 @@ xfs_growfs_data_private(
                         goto error0;
                 }
         }
+
+        /*
+         * Update changed superblock fields transactionally. These are not
+         * seen by the rest of the world until the transaction commit applies
+         * them atomically to the superblock.
+         */
         if (nagcount > oagcount)
                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
         if (nb > mp->m_sb.sb_dblocks)
@@ -369,9 +367,9 @@ xfs_growfs_data_private(
         if (dpct)
                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
         error = xfs_trans_commit(tp, 0);
-        if (error) {
+        if (error)
                 return error;
-        }
+
         /* New allocation groups fully initialized, so update mount struct */
         if (nagimax)
                 mp->m_maxagi = nagimax;
@@ -381,6 +379,8 @@ xfs_growfs_data_private(
                 mp->m_maxicount = icount << mp->m_sb.sb_inopblog;
         } else
                 mp->m_maxicount = 0;
+
+        /* update secondary superblocks. */
         for (agno = 1; agno < nagcount; agno++) {
                 error = xfs_read_buf(mp, mp->m_ddev_targp,
                                   XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
diff --git a/fs/xfs/xfs_ialloc.c b/fs/xfs/xfs_ialloc.c
index 884ee1367f46..52c9d006c0e6 100644
--- a/fs/xfs/xfs_ialloc.c
+++ b/fs/xfs/xfs_ialloc.c
@@ -383,11 +383,9 @@ xfs_ialloc_ag_alloc(
         newino = XFS_OFFBNO_TO_AGINO(args.mp, args.agbno, 0);
         be32_add_cpu(&agi->agi_count, newlen);
         be32_add_cpu(&agi->agi_freecount, newlen);
-        down_read(&args.mp->m_peraglock);
         pag = xfs_perag_get(args.mp, agno);
         pag->pagi_freecount += newlen;
         xfs_perag_put(pag);
-        up_read(&args.mp->m_peraglock);
         agi->agi_newino = cpu_to_be32(newino);
 
         /*
@@ -489,7 +487,6 @@ xfs_ialloc_ag_select(
          */
         agno = pagno;
         flags = XFS_ALLOC_FLAG_TRYLOCK;
-        down_read(&mp->m_peraglock);
         for (;;) {
                 pag = xfs_perag_get(mp, agno);
                 if (!pag->pagi_init) {
@@ -531,7 +528,6 @@ xfs_ialloc_ag_select(
                                         goto nextag;
                                 }
                                 xfs_perag_put(pag);
-                                up_read(&mp->m_peraglock);
                                 return agbp;
                         }
                 }
@@ -544,18 +540,14 @@ nextag:
                  * No point in iterating over the rest, if we're shutting
                  * down.
                  */
-                if (XFS_FORCED_SHUTDOWN(mp)) {
-                        up_read(&mp->m_peraglock);
+                if (XFS_FORCED_SHUTDOWN(mp))
                         return NULL;
-                }
                 agno++;
                 if (agno >= agcount)
                         agno = 0;
                 if (agno == pagno) {
-                        if (flags == 0) {
-                                up_read(&mp->m_peraglock);
+                        if (flags == 0)
                                 return NULL;
-                        }
                         flags = 0;
                 }
         }
@@ -777,16 +769,13 @@ nextag:
                         *inop = NULLFSINO;
                         return noroom ? ENOSPC : 0;
                 }
-                down_read(&mp->m_peraglock);
                 pag = xfs_perag_get(mp, tagno);
                 if (pag->pagi_inodeok == 0) {
                         xfs_perag_put(pag);
-                        up_read(&mp->m_peraglock);
                         goto nextag;
                 }
                 error = xfs_ialloc_read_agi(mp, tp, tagno, &agbp);
                 xfs_perag_put(pag);
-                up_read(&mp->m_peraglock);
                 if (error)
                         goto nextag;
                 agi = XFS_BUF_TO_AGI(agbp);
@@ -1015,9 +1004,7 @@ alloc_inode:
                 goto error0;
         be32_add_cpu(&agi->agi_freecount, -1);
         xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
-        down_read(&mp->m_peraglock);
         pag->pagi_freecount--;
-        up_read(&mp->m_peraglock);
 
         error = xfs_check_agi_freecount(cur, agi);
         if (error)
@@ -1100,9 +1087,7 @@ xfs_difree(
         /*
          * Get the allocation group header.
          */
-        down_read(&mp->m_peraglock);
         error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
-        up_read(&mp->m_peraglock);
         if (error) {
                 cmn_err(CE_WARN,
                         "xfs_difree: xfs_ialloc_read_agi() returned an error %d on %s.  Returning error.",
@@ -1169,11 +1154,9 @@ xfs_difree(
                 be32_add_cpu(&agi->agi_count, -ilen);
                 be32_add_cpu(&agi->agi_freecount, -(ilen - 1));
                 xfs_ialloc_log_agi(tp, agbp, XFS_AGI_COUNT | XFS_AGI_FREECOUNT);
-                down_read(&mp->m_peraglock);
                 pag = xfs_perag_get(mp, agno);
                 pag->pagi_freecount -= ilen - 1;
                 xfs_perag_put(pag);
-                up_read(&mp->m_peraglock);
                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_ICOUNT, -ilen);
                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -(ilen - 1));
 
@@ -1202,11 +1185,9 @@ xfs_difree(
                  */
                 be32_add_cpu(&agi->agi_freecount, 1);
                 xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
-                down_read(&mp->m_peraglock);
                 pag = xfs_perag_get(mp, agno);
                 pag->pagi_freecount++;
                 xfs_perag_put(pag);
-                up_read(&mp->m_peraglock);
                 xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, 1);
         }
 
@@ -1328,9 +1309,7 @@ xfs_imap(
                 xfs_buf_t       *agbp;  /* agi buffer */
                 int             i;      /* temp state */
 
-                down_read(&mp->m_peraglock);
                 error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
-                up_read(&mp->m_peraglock);
                 if (error) {
                         xfs_fs_cmn_err(CE_ALERT, mp, "xfs_imap: "
                                         "xfs_ialloc_read_agi() returned "
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index 62efab2f3839..940307a6a60b 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -420,9 +420,7 @@ xfs_bulkstat(
         while (XFS_BULKSTAT_UBLEFT(ubleft) && agno < mp->m_sb.sb_agcount) {
                 cond_resched();
                 bp = NULL;
-                down_read(&mp->m_peraglock);
                 error = xfs_ialloc_read_agi(mp, NULL, agno, &agbp);
-                up_read(&mp->m_peraglock);
                 if (error) {
                         /*
                          * Skip this allocation group and go to the next one.
@@ -849,9 +847,7 @@ xfs_inumbers(
         agbp = NULL;
         while (left > 0 && agno < mp->m_sb.sb_agcount) {
                 if (agbp == NULL) {
-                        down_read(&mp->m_peraglock);
                         error = xfs_ialloc_read_agi(mp, NULL, agno, &agbp);
-                        up_read(&mp->m_peraglock);
                         if (error) {
                                 /*
                                  * If we can't read the AGI of this ag,
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 9055b60730d0..c04dd83cb57c 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -209,13 +209,16 @@ STATIC void
 xfs_free_perag(
         xfs_mount_t     *mp)
 {
-        if (mp->m_perag) {
-                int     agno;
+        xfs_agnumber_t  agno;
+        struct xfs_perag *pag;
 
-                for (agno = 0; agno < mp->m_maxagi; agno++)
-                        if (mp->m_perag[agno].pagb_list)
-                                kmem_free(mp->m_perag[agno].pagb_list);
-                kmem_free(mp->m_perag);
+        for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
+                spin_lock(&mp->m_perag_lock);
+                pag = radix_tree_delete(&mp->m_perag_tree, agno);
+                spin_unlock(&mp->m_perag_lock);
+                ASSERT(pag);
+                kmem_free(pag->pagb_list);
+                kmem_free(pag);
         }
 }
 
@@ -389,10 +392,11 @@ xfs_initialize_perag_icache(
         }
 }
 
-xfs_agnumber_t
+int
 xfs_initialize_perag(
         xfs_mount_t     *mp,
-        xfs_agnumber_t  agcount)
+        xfs_agnumber_t  agcount,
+        xfs_agnumber_t  *maxagi)
 {
         xfs_agnumber_t  index, max_metadata;
         xfs_perag_t     *pag;
@@ -405,6 +409,33 @@ xfs_initialize_perag(
         agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
         ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
 
+        /*
+         * Walk the current per-ag tree so we don't try to initialise AGs
+         * that already exist (growfs case). Allocate and insert all the
+         * AGs we don't find ready for initialisation.
+         */
+        for (index = 0; index < agcount; index++) {
+                pag = xfs_perag_get(mp, index);
+                if (pag) {
+                        xfs_perag_put(pag);
+                        continue;
+                }
+                pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
+                if (!pag)
+                        return -ENOMEM;
+                if (radix_tree_preload(GFP_NOFS))
+                        return -ENOMEM;
+                spin_lock(&mp->m_perag_lock);
+                if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
+                        BUG();
+                        spin_unlock(&mp->m_perag_lock);
+                        kmem_free(pag);
+                        return -EEXIST;
+                }
+                spin_unlock(&mp->m_perag_lock);
+                radix_tree_preload_end();
+        }
+
         /* Clear the mount flag if no inode can overflow 32 bits
          * on this filesystem, or if specifically requested..
          */
@@ -454,7 +485,9 @@ xfs_initialize_perag(
                         xfs_perag_put(pag);
                 }
         }
-        return index;
+        if (maxagi)
+                *maxagi = index;
+        return 0;
 }
 
 void
@@ -1155,13 +1188,13 @@ xfs_mountfs(
         /*
          * Allocate and initialize the per-ag data.
          */
-        init_rwsem(&mp->m_peraglock);
-        mp->m_perag = kmem_zalloc(sbp->sb_agcount * sizeof(xfs_perag_t),
-                                  KM_MAYFAIL);
-        if (!mp->m_perag)
+        spin_lock_init(&mp->m_perag_lock);
+        INIT_RADIX_TREE(&mp->m_perag_tree, GFP_NOFS);
+        error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
+        if (error) {
+                cmn_err(CE_WARN, "XFS: Failed per-ag init: %d", error);
                 goto out_remove_uuid;
-
-        mp->m_maxagi = xfs_initialize_perag(mp, sbp->sb_agcount);
+        }
 
         if (!sbp->sb_logblocks) {
                 cmn_err(CE_WARN, "XFS: no log defined");
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index f8a68a2319b5..cfa7a5d22e72 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -207,8 +207,8 @@ typedef struct xfs_mount {
         uint                    m_ag_maxlevels; /* XFS_AG_MAXLEVELS */
         uint                    m_bm_maxlevels[2]; /* XFS_BM_MAXLEVELS */
         uint                    m_in_maxlevels; /* max inobt btree levels. */
-        struct xfs_perag        *m_perag;       /* per-ag accounting info */
-        struct rw_semaphore     m_peraglock;    /* lock for m_perag (pointer) */
+        struct radix_tree_root  m_perag_tree;   /* per-ag accounting info */
+        spinlock_t              m_perag_lock;   /* lock for m_perag_tree */
         struct mutex            m_growlock;     /* growfs mutex */
         int                     m_fixedfsid[2]; /* unchanged for life of FS */
         uint                    m_dmevmask;     /* DMI events for this FS */
@@ -389,7 +389,12 @@ xfs_daddr_to_agbno(struct xfs_mount *mp, xfs_daddr_t d)
 static inline struct xfs_perag *
 xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
 {
-        return &mp->m_perag[agno];
+        struct xfs_perag        *pag;
+
+        spin_lock(&mp->m_perag_lock);
+        pag = radix_tree_lookup(&mp->m_perag_tree, agno);
+        spin_unlock(&mp->m_perag_lock);
+        return pag;
 }
 
 static inline void
@@ -450,7 +455,8 @@ extern struct xfs_dmops xfs_dmcore_xfs;
 #endif  /* __KERNEL__ */
 
 extern void     xfs_mod_sb(struct xfs_trans *, __int64_t);
-extern xfs_agnumber_t   xfs_initialize_perag(struct xfs_mount *, xfs_agnumber_t);
+extern int      xfs_initialize_perag(struct xfs_mount *, xfs_agnumber_t,
+                                        xfs_agnumber_t *);
 extern void     xfs_sb_from_disk(struct xfs_sb *, struct xfs_dsb *);
 extern void     xfs_sb_to_disk(struct xfs_dsb *, struct xfs_sb *, __int64_t);