]> err.no Git - linux-2.6/blobdiff - fs/xfs/xfs_mount.c
[XFS] Radix tree based inode caching
[linux-2.6] / fs / xfs / xfs_mount.c
index 397730f570b9719e380e2049edd5511c1ba457fd..71f25947251d81479fe984f041522624e9940732 100644 (file)
@@ -52,21 +52,19 @@ STATIC void xfs_unmountfs_wait(xfs_mount_t *);
 
 #ifdef HAVE_PERCPU_SB
 STATIC void    xfs_icsb_destroy_counters(xfs_mount_t *);
-STATIC void    xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t, int);
+STATIC void    xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t,
+                                               int, int);
 STATIC void    xfs_icsb_sync_counters(xfs_mount_t *);
 STATIC int     xfs_icsb_modify_counters(xfs_mount_t *, xfs_sb_field_t,
-                                               int, int);
-STATIC int     xfs_icsb_modify_counters_locked(xfs_mount_t *, xfs_sb_field_t,
-                                               int, int);
+                                               int64_t, int);
 STATIC int     xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);
 
 #else
 
 #define xfs_icsb_destroy_counters(mp)                  do { } while (0)
-#define xfs_icsb_balance_counter(mp, a, b)             do { } while (0)
+#define xfs_icsb_balance_counter(mp, a, b, c)          do { } while (0)
 #define xfs_icsb_sync_counters(mp)                     do { } while (0)
 #define xfs_icsb_modify_counters(mp, a, b, c)          do { } while (0)
-#define xfs_icsb_modify_counters_locked(mp, a, b, c)   do { } while (0)
 
 #endif
 
@@ -162,11 +160,6 @@ xfs_mount_free(
        xfs_mount_t     *mp,
        int             remove_bhv)
 {
-       if (mp->m_ihash)
-               xfs_ihash_free(mp);
-       if (mp->m_chash)
-               xfs_chash_free(mp);
-
        if (mp->m_perag) {
                int     agno;
 
@@ -204,6 +197,27 @@ xfs_mount_free(
        kmem_free(mp, sizeof(xfs_mount_t));
 }
 
+/*
+ * Check size of device based on the (data/realtime) block count.
+ * Note: this check is used by the growfs code as well as mount.
+ */
+int
+xfs_sb_validate_fsb_count(
+       xfs_sb_t        *sbp,
+       __uint64_t      nblocks)
+{
+       ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
+       ASSERT(sbp->sb_blocklog >= BBSHIFT);
+
+#if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
+       if (nblocks >> (PAGE_CACHE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
+               return E2BIG;
+#else                  /* Limited by UINT_MAX of sectors */
+       if (nblocks << (sbp->sb_blocklog - BBSHIFT) > UINT_MAX)
+               return E2BIG;
+#endif
+       return 0;
+}
 
 /*
  * Check the validity of the SB found.
@@ -286,18 +300,8 @@ xfs_mount_validate_sb(
                return XFS_ERROR(EFSCORRUPTED);
        }
 
-       ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
-       ASSERT(sbp->sb_blocklog >= BBSHIFT);
-
-#if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
-       if (unlikely(
-           (sbp->sb_dblocks >> (PAGE_SHIFT - sbp->sb_blocklog)) > ULONG_MAX ||
-           (sbp->sb_rblocks >> (PAGE_SHIFT - sbp->sb_blocklog)) > ULONG_MAX)) {
-#else                  /* Limited by UINT_MAX of sectors */
-       if (unlikely(
-           (sbp->sb_dblocks << (sbp->sb_blocklog - BBSHIFT)) > UINT_MAX ||
-           (sbp->sb_rblocks << (sbp->sb_blocklog - BBSHIFT)) > UINT_MAX)) {
-#endif
+       if (xfs_sb_validate_fsb_count(sbp, sbp->sb_dblocks) ||
+           xfs_sb_validate_fsb_count(sbp, sbp->sb_rblocks)) {
                xfs_fs_mount_cmn_err(flags,
                        "file system too large to be mounted on this system.");
                return XFS_ERROR(E2BIG);
@@ -333,6 +337,17 @@ xfs_mount_validate_sb(
        return 0;
 }
 
+STATIC void
+xfs_initialize_perag_icache(
+       xfs_perag_t     *pag)
+{
+       if (!pag->pag_ici_init) {
+               rwlock_init(&pag->pag_ici_lock);
+               INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
+               pag->pag_ici_init = 1;
+       }
+}
+
 xfs_agnumber_t
 xfs_initialize_perag(
        bhv_vfs_t       *vfs,
@@ -387,48 +402,92 @@ xfs_initialize_perag(
                        pag->pagi_inodeok = 1;
                        if (index < max_metadata)
                                pag->pagf_metadata = 1;
+                       xfs_initialize_perag_icache(pag);
                }
        } else {
                /* Setup default behavior for smaller filesystems */
                for (index = 0; index < agcount; index++) {
                        pag = &mp->m_perag[index];
                        pag->pagi_inodeok = 1;
+                       xfs_initialize_perag_icache(pag);
                }
        }
        return index;
 }
 
+void
+xfs_sb_from_disk(
+       xfs_sb_t        *to,
+       xfs_dsb_t       *from)
+{
+       to->sb_magicnum = be32_to_cpu(from->sb_magicnum);
+       to->sb_blocksize = be32_to_cpu(from->sb_blocksize);
+       to->sb_dblocks = be64_to_cpu(from->sb_dblocks);
+       to->sb_rblocks = be64_to_cpu(from->sb_rblocks);
+       to->sb_rextents = be64_to_cpu(from->sb_rextents);
+       memcpy(&to->sb_uuid, &from->sb_uuid, sizeof(to->sb_uuid));
+       to->sb_logstart = be64_to_cpu(from->sb_logstart);
+       to->sb_rootino = be64_to_cpu(from->sb_rootino);
+       to->sb_rbmino = be64_to_cpu(from->sb_rbmino);
+       to->sb_rsumino = be64_to_cpu(from->sb_rsumino);
+       to->sb_rextsize = be32_to_cpu(from->sb_rextsize);
+       to->sb_agblocks = be32_to_cpu(from->sb_agblocks);
+       to->sb_agcount = be32_to_cpu(from->sb_agcount);
+       to->sb_rbmblocks = be32_to_cpu(from->sb_rbmblocks);
+       to->sb_logblocks = be32_to_cpu(from->sb_logblocks);
+       to->sb_versionnum = be16_to_cpu(from->sb_versionnum);
+       to->sb_sectsize = be16_to_cpu(from->sb_sectsize);
+       to->sb_inodesize = be16_to_cpu(from->sb_inodesize);
+       to->sb_inopblock = be16_to_cpu(from->sb_inopblock);
+       memcpy(&to->sb_fname, &from->sb_fname, sizeof(to->sb_fname));
+       to->sb_blocklog = from->sb_blocklog;
+       to->sb_sectlog = from->sb_sectlog;
+       to->sb_inodelog = from->sb_inodelog;
+       to->sb_inopblog = from->sb_inopblog;
+       to->sb_agblklog = from->sb_agblklog;
+       to->sb_rextslog = from->sb_rextslog;
+       to->sb_inprogress = from->sb_inprogress;
+       to->sb_imax_pct = from->sb_imax_pct;
+       to->sb_icount = be64_to_cpu(from->sb_icount);
+       to->sb_ifree = be64_to_cpu(from->sb_ifree);
+       to->sb_fdblocks = be64_to_cpu(from->sb_fdblocks);
+       to->sb_frextents = be64_to_cpu(from->sb_frextents);
+       to->sb_uquotino = be64_to_cpu(from->sb_uquotino);
+       to->sb_gquotino = be64_to_cpu(from->sb_gquotino);
+       to->sb_qflags = be16_to_cpu(from->sb_qflags);
+       to->sb_flags = from->sb_flags;
+       to->sb_shared_vn = from->sb_shared_vn;
+       to->sb_inoalignmt = be32_to_cpu(from->sb_inoalignmt);
+       to->sb_unit = be32_to_cpu(from->sb_unit);
+       to->sb_width = be32_to_cpu(from->sb_width);
+       to->sb_dirblklog = from->sb_dirblklog;
+       to->sb_logsectlog = from->sb_logsectlog;
+       to->sb_logsectsize = be16_to_cpu(from->sb_logsectsize);
+       to->sb_logsunit = be32_to_cpu(from->sb_logsunit);
+       to->sb_features2 = be32_to_cpu(from->sb_features2);
+}
+
 /*
- * xfs_xlatesb
+ * Copy in core superblock to ondisk one.
  *
- *     data       - on disk version of sb
- *     sb         - a superblock
- *     dir        - conversion direction: <0 - convert sb to buf
- *                                        >0 - convert buf to sb
- *     fields     - which fields to copy (bitmask)
+ * The fields argument is mask of superblock fields to copy.
  */
 void
-xfs_xlatesb(
-       void            *data,
-       xfs_sb_t        *sb,
-       int             dir,
+xfs_sb_to_disk(
+       xfs_dsb_t       *to,
+       xfs_sb_t        *from,
        __int64_t       fields)
 {
-       xfs_caddr_t     buf_ptr;
-       xfs_caddr_t     mem_ptr;
+       xfs_caddr_t     to_ptr = (xfs_caddr_t)to;
+       xfs_caddr_t     from_ptr = (xfs_caddr_t)from;
        xfs_sb_field_t  f;
        int             first;
        int             size;
 
-       ASSERT(dir);
        ASSERT(fields);
-
        if (!fields)
                return;
 
-       buf_ptr = (xfs_caddr_t)data;
-       mem_ptr = (xfs_caddr_t)sb;
-
        while (fields) {
                f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
                first = xfs_sb_info[f].offset;
@@ -437,26 +496,20 @@ xfs_xlatesb(
                ASSERT(xfs_sb_info[f].type == 0 || xfs_sb_info[f].type == 1);
 
                if (size == 1 || xfs_sb_info[f].type == 1) {
-                       if (dir > 0) {
-                               memcpy(mem_ptr + first, buf_ptr + first, size);
-                       } else {
-                               memcpy(buf_ptr + first, mem_ptr + first, size);
-                       }
+                       memcpy(to_ptr + first, from_ptr + first, size);
                } else {
                        switch (size) {
                        case 2:
-                               INT_XLATE(*(__uint16_t*)(buf_ptr+first),
-                                         *(__uint16_t*)(mem_ptr+first),
-                                         dir, ARCH_CONVERT);
+                               *(__be16 *)(to_ptr + first) =
+                                       cpu_to_be16(*(__u16 *)(from_ptr + first));
                                break;
                        case 4:
-                               INT_XLATE(*(__uint32_t*)(buf_ptr+first),
-                                         *(__uint32_t*)(mem_ptr+first),
-                                         dir, ARCH_CONVERT);
+                               *(__be32 *)(to_ptr + first) =
+                                       cpu_to_be32(*(__u32 *)(from_ptr + first));
                                break;
                        case 8:
-                               INT_XLATE(*(__uint64_t*)(buf_ptr+first),
-                                         *(__uint64_t*)(mem_ptr+first), dir, ARCH_CONVERT);
+                               *(__be64 *)(to_ptr + first) =
+                                       cpu_to_be64(*(__u64 *)(from_ptr + first));
                                break;
                        default:
                                ASSERT(0);
@@ -478,7 +531,6 @@ xfs_readsb(xfs_mount_t *mp, int flags)
        unsigned int    sector_size;
        unsigned int    extra_flags;
        xfs_buf_t       *bp;
-       xfs_sb_t        *sbp;
        int             error;
 
        ASSERT(mp->m_sb_bp == NULL);
@@ -506,8 +558,7 @@ xfs_readsb(xfs_mount_t *mp, int flags)
         * Initialize the mount structure from the superblock.
         * But first do some basic consistency checking.
         */
-       sbp = XFS_BUF_TO_SBP(bp);
-       xfs_xlatesb(XFS_BUF_PTR(bp), &(mp->m_sb), 1, XFS_SB_ALL_BITS);
+       xfs_sb_from_disk(&mp->m_sb, XFS_BUF_TO_SBP(bp));
 
        error = xfs_mount_validate_sb(mp, &(mp->m_sb), flags);
        if (error) {
@@ -545,9 +596,8 @@ xfs_readsb(xfs_mount_t *mp, int flags)
                ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
        }
 
-       xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
-       xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
-       xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
+       /* Initialize per-cpu counters */
+       xfs_icsb_reinit_counters(mp);
 
        mp->m_sb_bp = bp;
        xfs_buf_relse(bp);
@@ -635,6 +685,64 @@ xfs_mount_common(xfs_mount_t *mp, xfs_sb_t *sbp)
                                        sbp->sb_inopblock);
        mp->m_ialloc_blks = mp->m_ialloc_inos >> sbp->sb_inopblog;
 }
+
+/*
+ * xfs_initialize_perag_data
+ *
+ * Read in each per-ag structure so we can count up the number of
+ * allocated inodes, free inodes and used filesystem blocks as this
+ * information is no longer persistent in the superblock. Once we have
+ * this information, write it into the in-core superblock structure.
+ */
+STATIC int
+xfs_initialize_perag_data(xfs_mount_t *mp, xfs_agnumber_t agcount)
+{
+       xfs_agnumber_t  index;
+       xfs_perag_t     *pag;
+       xfs_sb_t        *sbp = &mp->m_sb;
+       uint64_t        ifree = 0;
+       uint64_t        ialloc = 0;
+       uint64_t        bfree = 0;
+       uint64_t        bfreelst = 0;
+       uint64_t        btree = 0;
+       int             error;
+       int             s;
+
+       for (index = 0; index < agcount; index++) {
+               /*
+                * read the agf, then the agi. This gets us
+                * all the inforamtion we need and populates the
+                * per-ag structures for us.
+                */
+               error = xfs_alloc_pagf_init(mp, NULL, index, 0);
+               if (error)
+                       return error;
+
+               error = xfs_ialloc_pagi_init(mp, NULL, index);
+               if (error)
+                       return error;
+               pag = &mp->m_perag[index];
+               ifree += pag->pagi_freecount;
+               ialloc += pag->pagi_count;
+               bfree += pag->pagf_freeblks;
+               bfreelst += pag->pagf_flcount;
+               btree += pag->pagf_btreeblks;
+       }
+       /*
+        * Overwrite incore superblock counters with just-read data
+        */
+       s = XFS_SB_LOCK(mp);
+       sbp->sb_ifree = ifree;
+       sbp->sb_icount = ialloc;
+       sbp->sb_fdblocks = bfree + bfreelst + btree;
+       XFS_SB_UNLOCK(mp, s);
+
+       /* Fixup the per-cpu counters as well. */
+       xfs_icsb_reinit_counters(mp);
+
+       return 0;
+}
+
 /*
  * xfs_mountfs
  *
@@ -659,7 +767,7 @@ xfs_mountfs(
        bhv_vnode_t     *rvp = NULL;
        int             readio_log, writeio_log;
        xfs_daddr_t     d;
-       __uint64_t      ret64;
+       __uint64_t      resblks;
        __int64_t       update_flags;
        uint            quotamount, quotaflags;
        int             agno;
@@ -776,6 +884,7 @@ xfs_mountfs(
         */
        if ((mfsi_flags & XFS_MFSI_SECOND) == 0 &&
            (mp->m_flags & XFS_MOUNT_NOUUID) == 0) {
+               __uint64_t      ret64;
                if (xfs_uuid_mount(mp)) {
                        error = XFS_ERROR(EINVAL);
                        goto error1;
@@ -804,16 +913,6 @@ xfs_mountfs(
                writeio_log = mp->m_writeio_log;
        }
 
-       /*
-        * Set the number of readahead buffers to use based on
-        * physical memory size.
-        */
-       if (xfs_physmem <= 4096)                /* <= 16MB */
-               mp->m_nreadaheads = XFS_RW_NREADAHEAD_16MB;
-       else if (xfs_physmem <= 8192)   /* <= 32MB */
-               mp->m_nreadaheads = XFS_RW_NREADAHEAD_32MB;
-       else
-               mp->m_nreadaheads = XFS_RW_NREADAHEAD_K32;
        if (sbp->sb_blocklog > readio_log) {
                mp->m_readio_log = sbp->sb_blocklog;
        } else {
@@ -828,15 +927,12 @@ xfs_mountfs(
        mp->m_writeio_blocks = 1 << (mp->m_writeio_log - sbp->sb_blocklog);
 
        /*
-        * Set the inode cluster size based on the physical memory
-        * size.  This may still be overridden by the file system
+        * Set the inode cluster size.
+        * This may still be overridden by the file system
         * block size if it is larger than the chosen cluster size.
         */
-       if (xfs_physmem <= btoc(32 * 1024 * 1024)) { /* <= 32 MB */
-               mp->m_inode_cluster_size = XFS_INODE_SMALL_CLUSTER_SIZE;
-       } else {
-               mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
-       }
+       mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
+
        /*
         * Set whether we're using inode alignment.
         */
@@ -944,13 +1040,6 @@ xfs_mountfs(
         */
        xfs_trans_init(mp);
 
-       /*
-        * Allocate and initialize the inode hash table for this
-        * file system.
-        */
-       xfs_ihash_init(mp);
-       xfs_chash_init(mp);
-
        /*
         * Allocate and initialize the per-ag data.
         */
@@ -978,6 +1067,34 @@ xfs_mountfs(
                goto error2;
        }
 
+       /*
+        * Now the log is mounted, we know if it was an unclean shutdown or
+        * not. If it was, with the first phase of recovery has completed, we
+        * have consistent AG blocks on disk. We have not recovered EFIs yet,
+        * but they are recovered transactionally in the second recovery phase
+        * later.
+        *
+        * Hence we can safely re-initialise incore superblock counters from
+        * the per-ag data. These may not be correct if the filesystem was not
+        * cleanly unmounted, so we need to wait for recovery to finish before
+        * doing this.
+        *
+        * If the filesystem was cleanly unmounted, then we can trust the
+        * values in the superblock to be correct and we don't need to do
+        * anything here.
+        *
+        * If we are currently making the filesystem, the initialisation will
+        * fail as the perag data is in an undefined state.
+        */
+
+       if (xfs_sb_version_haslazysbcount(&mp->m_sb) &&
+           !XFS_LAST_UNMOUNT_WAS_CLEAN(mp) &&
+            !mp->m_sb.sb_inprogress) {
+               error = xfs_initialize_perag_data(mp, sbp->sb_agcount);
+               if (error) {
+                       goto error2;
+               }
+       }
        /*
         * Get and sanity-check the root inode.
         * Save the pointer to it in the mount structure.
@@ -1047,6 +1164,23 @@ xfs_mountfs(
        if ((error = XFS_QM_MOUNT(mp, quotamount, quotaflags, mfsi_flags)))
                goto error4;
 
+       /*
+        * Now we are mounted, reserve a small amount of unused space for
+        * privileged transactions. This is needed so that transaction
+        * space required for critical operations can dip into this pool
+        * when at ENOSPC. This is needed for operations like create with
+        * attr, unwritten extent conversion at ENOSPC, etc. Data allocations
+        * are not allowed to use this reserved space.
+        *
+        * We default to 5% or 1024 fsbs of space reserved, whichever is smaller.
+        * This may drive us straight to ENOSPC on mount, but that implies
+        * we were already there on the last unmount.
+        */
+       resblks = mp->m_sb.sb_dblocks;
+       do_div(resblks, 20);
+       resblks = min_t(__uint64_t, resblks, 1024);
+       xfs_reserve_blocks(mp, &resblks, NULL);
+
        return 0;
 
  error4:
@@ -1057,8 +1191,6 @@ xfs_mountfs(
  error3:
        xfs_log_unmount_dealloc(mp);
  error2:
-       xfs_ihash_free(mp);
-       xfs_chash_free(mp);
        for (agno = 0; agno < sbp->sb_agcount; agno++)
                if (mp->m_perag[agno].pagb_list)
                        kmem_free(mp->m_perag[agno].pagb_list,
@@ -1086,7 +1218,19 @@ xfs_unmountfs(xfs_mount_t *mp, struct cred *cr)
 #if defined(DEBUG) || defined(INDUCE_IO_ERROR)
        int64_t         fsid;
 #endif
+       __uint64_t      resblks;
 
+       /*
+        * We can potentially deadlock here if we have an inode cluster
+        * that has been freed has it's buffer still pinned in memory because
+        * the transaction is still sitting in a iclog. The stale inodes
+        * on that buffer will have their flush locks held until the
+        * transaction hits the disk and the callbacks run. the inode
+        * flush takes the flush lock unconditionally and with nothing to
+        * push out the iclog we will never get that unlocked. hence we
+        * need to force the log first.
+        */
+       xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE | XFS_LOG_SYNC);
        xfs_iflush_all(mp);
 
        XFS_QM_DQPURGEALL(mp, XFS_QMOPT_QUOTALL | XFS_QMOPT_UMOUNTING);
@@ -1103,10 +1247,26 @@ xfs_unmountfs(xfs_mount_t *mp, struct cred *cr)
                xfs_binval(mp->m_rtdev_targp);
        }
 
-       xfs_unmountfs_writesb(mp);
+       /*
+        * Unreserve any blocks we have so that when we unmount we don't account
+        * the reserved free space as used. This is really only necessary for
+        * lazy superblock counting because it trusts the incore superblock
+        * counters to be aboslutely correct on clean unmount.
+        *
+        * We don't bother correcting this elsewhere for lazy superblock
+        * counting because on mount of an unclean filesystem we reconstruct the
+        * correct counter value and this is irrelevant.
+        *
+        * For non-lazy counter filesystems, this doesn't matter at all because
+        * we only every apply deltas to the superblock and hence the incore
+        * value does not matter....
+        */
+       resblks = 0;
+       xfs_reserve_blocks(mp, &resblks, NULL);
 
+       xfs_log_sbcount(mp, 1);
+       xfs_unmountfs_writesb(mp);
        xfs_unmountfs_wait(mp);                 /* wait for async bufs */
-
        xfs_log_unmount(mp);                    /* Done! No more fs ops. */
 
        xfs_freesb(mp);
@@ -1135,7 +1295,7 @@ xfs_unmountfs(xfs_mount_t *mp, struct cred *cr)
 void
 xfs_unmountfs_close(xfs_mount_t *mp, struct cred *cr)
 {
-       if (mp->m_logdev_targp != mp->m_ddev_targp)
+       if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
                xfs_free_buftarg(mp->m_logdev_targp, 1);
        if (mp->m_rtdev_targp)
                xfs_free_buftarg(mp->m_rtdev_targp, 1);
@@ -1152,35 +1312,101 @@ xfs_unmountfs_wait(xfs_mount_t *mp)
        xfs_wait_buftarg(mp->m_ddev_targp);
 }
 
+int
+xfs_fs_writable(xfs_mount_t *mp)
+{
+       bhv_vfs_t       *vfsp = XFS_MTOVFS(mp);
+
+       return !(vfs_test_for_freeze(vfsp) || XFS_FORCED_SHUTDOWN(mp) ||
+               (vfsp->vfs_flag & VFS_RDONLY));
+}
+
+/*
+ * xfs_log_sbcount
+ *
+ * Called either periodically to keep the on disk superblock values
+ * roughly up to date or from unmount to make sure the values are
+ * correct on a clean unmount.
+ *
+ * Note this code can be called during the process of freezing, so
+ * we may need to use the transaction allocator which does not not
+ * block when the transaction subsystem is in its frozen state.
+ */
+int
+xfs_log_sbcount(
+       xfs_mount_t     *mp,
+       uint            sync)
+{
+       xfs_trans_t     *tp;
+       int             error;
+
+       if (!xfs_fs_writable(mp))
+               return 0;
+
+       xfs_icsb_sync_counters(mp);
+
+       /*
+        * we don't need to do this if we are updating the superblock
+        * counters on every modification.
+        */
+       if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
+               return 0;
+
+       tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT);
+       error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
+                                       XFS_DEFAULT_LOG_COUNT);
+       if (error) {
+               xfs_trans_cancel(tp, 0);
+               return error;
+       }
+
+       xfs_mod_sb(tp, XFS_SB_IFREE | XFS_SB_ICOUNT | XFS_SB_FDBLOCKS);
+       if (sync)
+               xfs_trans_set_sync(tp);
+       xfs_trans_commit(tp, 0);
+
+       return 0;
+}
+
+STATIC void
+xfs_mark_shared_ro(
+       xfs_mount_t     *mp,
+       xfs_buf_t       *bp)
+{
+       xfs_dsb_t       *sb = XFS_BUF_TO_SBP(bp);
+       __uint16_t      version;
+
+       if (!(sb->sb_flags & XFS_SBF_READONLY))
+               sb->sb_flags |= XFS_SBF_READONLY;
+
+       version = be16_to_cpu(sb->sb_versionnum);
+       if ((version & XFS_SB_VERSION_NUMBITS) != XFS_SB_VERSION_4 ||
+           !(version & XFS_SB_VERSION_SHAREDBIT))
+               version |= XFS_SB_VERSION_SHAREDBIT;
+       sb->sb_versionnum = cpu_to_be16(version);
+}
+
 int
 xfs_unmountfs_writesb(xfs_mount_t *mp)
 {
        xfs_buf_t       *sbp;
-       xfs_sb_t        *sb;
        int             error = 0;
 
        /*
         * skip superblock write if fs is read-only, or
         * if we are doing a forced umount.
         */
-       sbp = xfs_getsb(mp, 0);
        if (!(XFS_MTOVFS(mp)->vfs_flag & VFS_RDONLY ||
                XFS_FORCED_SHUTDOWN(mp))) {
 
-               xfs_icsb_sync_counters(mp);
+               sbp = xfs_getsb(mp, 0);
 
                /*
                 * mark shared-readonly if desired
                 */
-               sb = XFS_BUF_TO_SBP(sbp);
-               if (mp->m_mk_sharedro) {
-                       if (!(sb->sb_flags & XFS_SBF_READONLY))
-                               sb->sb_flags |= XFS_SBF_READONLY;
-                       if (!XFS_SB_VERSION_HASSHARED(sb))
-                               XFS_SB_VERSION_ADDSHARED(sb);
-                       xfs_fs_cmn_err(CE_NOTE, mp,
-                               "Unmounting, marking shared read-only");
-               }
+               if (mp->m_mk_sharedro)
+                       xfs_mark_shared_ro(mp, sbp);
+
                XFS_BUF_UNDONE(sbp);
                XFS_BUF_UNREAD(sbp);
                XFS_BUF_UNDELAYWRITE(sbp);
@@ -1195,8 +1421,8 @@ xfs_unmountfs_writesb(xfs_mount_t *mp)
                                          mp, sbp, XFS_BUF_ADDR(sbp));
                if (error && mp->m_mk_sharedro)
                        xfs_fs_cmn_err(CE_ALERT, mp, "Superblock write error detected while unmounting.  Filesystem may not be marked shared readonly");
+               xfs_buf_relse(sbp);
        }
-       xfs_buf_relse(sbp);
        return error;
 }
 
@@ -1214,7 +1440,6 @@ xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
        int             first;
        int             last;
        xfs_mount_t     *mp;
-       xfs_sb_t        *sbp;
        xfs_sb_field_t  f;
 
        ASSERT(fields);
@@ -1222,13 +1447,12 @@ xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
                return;
        mp = tp->t_mountp;
        bp = xfs_trans_getsb(tp, mp, 0);
-       sbp = XFS_BUF_TO_SBP(bp);
        first = sizeof(xfs_sb_t);
        last = 0;
 
        /* translate/copy */
 
-       xfs_xlatesb(XFS_BUF_PTR(bp), &(mp->m_sb), -1, fields);
+       xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, fields);
 
        /* find modified range */
 
@@ -1254,8 +1478,11 @@ xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
  * The SB_LOCK must be held when this routine is called.
  */
 int
-xfs_mod_incore_sb_unlocked(xfs_mount_t *mp, xfs_sb_field_t field,
-                       int delta, int rsvd)
+xfs_mod_incore_sb_unlocked(
+       xfs_mount_t     *mp,
+       xfs_sb_field_t  field,
+       int64_t         delta,
+       int             rsvd)
 {
        int             scounter;       /* short counter for 32 bit fields */
        long long       lcounter;       /* long counter for 64 bit fields */
@@ -1287,7 +1514,6 @@ xfs_mod_incore_sb_unlocked(xfs_mount_t *mp, xfs_sb_field_t field,
                mp->m_sb.sb_ifree = lcounter;
                return 0;
        case XFS_SBS_FDBLOCKS:
-
                lcounter = (long long)
                        mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
                res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
@@ -1418,7 +1644,11 @@ xfs_mod_incore_sb_unlocked(xfs_mount_t *mp, xfs_sb_field_t field,
  * routine to do the work.
  */
 int
-xfs_mod_incore_sb(xfs_mount_t *mp, xfs_sb_field_t field, int delta, int rsvd)
+xfs_mod_incore_sb(
+       xfs_mount_t     *mp,
+       xfs_sb_field_t  field,
+       int64_t         delta,
+       int             rsvd)
 {
        unsigned long   s;
        int     status;
@@ -1485,9 +1715,11 @@ xfs_mod_incore_sb_batch(xfs_mount_t *mp, xfs_mod_sb_t *msb, uint nmsb, int rsvd)
                case XFS_SBS_IFREE:
                case XFS_SBS_FDBLOCKS:
                        if (!(mp->m_flags & XFS_MOUNT_NO_PERCPU_SB)) {
-                               status = xfs_icsb_modify_counters_locked(mp,
+                               XFS_SB_UNLOCK(mp, s);
+                               status = xfs_icsb_modify_counters(mp,
                                                        msbp->msb_field,
                                                        msbp->msb_delta, rsvd);
+                               s = XFS_SB_LOCK(mp);
                                break;
                        }
                        /* FALLTHROUGH */
@@ -1521,11 +1753,12 @@ xfs_mod_incore_sb_batch(xfs_mount_t *mp, xfs_mod_sb_t *msb, uint nmsb, int rsvd)
                        case XFS_SBS_IFREE:
                        case XFS_SBS_FDBLOCKS:
                                if (!(mp->m_flags & XFS_MOUNT_NO_PERCPU_SB)) {
-                                       status =
-                                           xfs_icsb_modify_counters_locked(mp,
+                                       XFS_SB_UNLOCK(mp, s);
+                                       status = xfs_icsb_modify_counters(mp,
                                                        msbp->msb_field,
                                                        -(msbp->msb_delta),
                                                        rsvd);
+                                       s = XFS_SB_LOCK(mp);
                                        break;
                                }
                                /* FALLTHROUGH */
@@ -1647,7 +1880,7 @@ xfs_mount_log_sbunit(
                return;
        }
        xfs_mod_sb(tp, fields);
-       xfs_trans_commit(tp, 0, NULL);
+       xfs_trans_commit(tp, 0);
 }
 
 
@@ -1728,19 +1961,25 @@ xfs_icsb_cpu_notify(
                        per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu);
        switch (action) {
        case CPU_UP_PREPARE:
+       case CPU_UP_PREPARE_FROZEN:
                /* Easy Case - initialize the area and locks, and
                 * then rebalance when online does everything else for us. */
                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
                break;
        case CPU_ONLINE:
-               xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
-               xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
-               xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
+       case CPU_ONLINE_FROZEN:
+               xfs_icsb_lock(mp);
+               xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0, 0);
+               xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0, 0);
+               xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0, 0);
+               xfs_icsb_unlock(mp);
                break;
        case CPU_DEAD:
+       case CPU_DEAD_FROZEN:
                /* Disable all the counters, then fold the dead cpu's
                 * count into the total on the global superblock and
                 * re-enable the counters. */
+               xfs_icsb_lock(mp);
                s = XFS_SB_LOCK(mp);
                xfs_icsb_disable_counter(mp, XFS_SBS_ICOUNT);
                xfs_icsb_disable_counter(mp, XFS_SBS_IFREE);
@@ -1752,10 +1991,14 @@ xfs_icsb_cpu_notify(
 
                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
 
-               xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, XFS_ICSB_SB_LOCKED);
-               xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, XFS_ICSB_SB_LOCKED);
-               xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, XFS_ICSB_SB_LOCKED);
+               xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT,
+                                        XFS_ICSB_SB_LOCKED, 0);
+               xfs_icsb_balance_counter(mp, XFS_SBS_IFREE,
+                                        XFS_ICSB_SB_LOCKED, 0);
+               xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS,
+                                        XFS_ICSB_SB_LOCKED, 0);
                XFS_SB_UNLOCK(mp, s);
+               xfs_icsb_unlock(mp);
                break;
        }
 
@@ -1784,6 +2027,9 @@ xfs_icsb_init_counters(
                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
        }
+
+       mutex_init(&mp->m_icsb_mutex);
+
        /*
         * start with all counters disabled so that the
         * initial balance kicks us off correctly
@@ -1792,6 +2038,22 @@ xfs_icsb_init_counters(
        return 0;
 }
 
+void
+xfs_icsb_reinit_counters(
+       xfs_mount_t     *mp)
+{
+       xfs_icsb_lock(mp);
+       /*
+        * start with all counters disabled so that the
+        * initial balance kicks us off correctly
+        */
+       mp->m_icsb_counters = -1;
+       xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0, 0);
+       xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0, 0);
+       xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0, 0);
+       xfs_icsb_unlock(mp);
+}
+
 STATIC void
 xfs_icsb_destroy_counters(
        xfs_mount_t     *mp)
@@ -1800,6 +2062,7 @@ xfs_icsb_destroy_counters(
                unregister_hotcpu_notifier(&mp->m_icsb_notifier);
                free_percpu(mp->m_sb_cnts);
        }
+       mutex_destroy(&mp->m_icsb_mutex);
 }
 
 STATIC_INLINE void
@@ -1888,6 +2151,17 @@ xfs_icsb_disable_counter(
 
        ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
 
+       /*
+        * If we are already disabled, then there is nothing to do
+        * here. We check before locking all the counters to avoid
+        * the expensive lock operation when being called in the
+        * slow path and the counter is already disabled. This is
+        * safe because the only time we set or clear this state is under
+        * the m_icsb_mutex.
+        */
+       if (xfs_icsb_counter_disabled(mp, field))
+               return 0;
+
        xfs_icsb_lock_all_counters(mp);
        if (!test_and_set_bit(field, &mp->m_icsb_counters)) {
                /* drain back to superblock */
@@ -1948,8 +2222,8 @@ xfs_icsb_enable_counter(
        xfs_icsb_unlock_all_counters(mp);
 }
 
-STATIC void
-xfs_icsb_sync_counters_int(
+void
+xfs_icsb_sync_counters_flags(
        xfs_mount_t     *mp,
        int             flags)
 {
@@ -1981,40 +2255,39 @@ STATIC void
 xfs_icsb_sync_counters(
        xfs_mount_t     *mp)
 {
-       xfs_icsb_sync_counters_int(mp, 0);
-}
-
-/*
- * lazy addition used for things like df, background sb syncs, etc
- */
-void
-xfs_icsb_sync_counters_lazy(
-       xfs_mount_t     *mp)
-{
-       xfs_icsb_sync_counters_int(mp, XFS_ICSB_LAZY_COUNT);
+       xfs_icsb_sync_counters_flags(mp, 0);
 }
 
 /*
  * Balance and enable/disable counters as necessary.
  *
- * Thresholds for re-enabling counters are somewhat magic.
- * inode counts are chosen to be the same number as single
- * on disk allocation chunk per CPU, and free blocks is
- * something far enough zero that we aren't going thrash
- * when we get near ENOSPC.
+ * Thresholds for re-enabling counters are somewhat magic.  inode counts are
+ * chosen to be the same number as single on disk allocation chunk per CPU, and
+ * free blocks is something far enough zero that we aren't going thrash when we
+ * get near ENOSPC. We also need to supply a minimum we require per cpu to
+ * prevent looping endlessly when xfs_alloc_space asks for more than will
+ * be distributed to a single CPU but each CPU has enough blocks to be
+ * reenabled.
+ *
+ * Note that we can be called when counters are already disabled.
+ * xfs_icsb_disable_counter() optimises the counter locking in this case to
+ * prevent locking every per-cpu counter needlessly.
  */
-#define XFS_ICSB_INO_CNTR_REENABLE     64
+
+#define XFS_ICSB_INO_CNTR_REENABLE     (uint64_t)64
 #define XFS_ICSB_FDBLK_CNTR_REENABLE(mp) \
-               (512 + XFS_ALLOC_SET_ASIDE(mp))
+               (uint64_t)(512 + XFS_ALLOC_SET_ASIDE(mp))
 STATIC void
 xfs_icsb_balance_counter(
        xfs_mount_t     *mp,
        xfs_sb_field_t  field,
-       int             flags)
+       int             flags,
+       int             min_per_cpu)
 {
        uint64_t        count, resid;
        int             weight = num_online_cpus();
        int             s;
+       uint64_t        min = (uint64_t)min_per_cpu;
 
        if (!(flags & XFS_ICSB_SB_LOCKED))
                s = XFS_SB_LOCK(mp);
@@ -2027,19 +2300,19 @@ xfs_icsb_balance_counter(
        case XFS_SBS_ICOUNT:
                count = mp->m_sb.sb_icount;
                resid = do_div(count, weight);
-               if (count < XFS_ICSB_INO_CNTR_REENABLE)
+               if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
                        goto out;
                break;
        case XFS_SBS_IFREE:
                count = mp->m_sb.sb_ifree;
                resid = do_div(count, weight);
-               if (count < XFS_ICSB_INO_CNTR_REENABLE)
+               if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
                        goto out;
                break;
        case XFS_SBS_FDBLOCKS:
                count = mp->m_sb.sb_fdblocks;
                resid = do_div(count, weight);
-               if (count < XFS_ICSB_FDBLK_CNTR_REENABLE(mp))
+               if (count < max(min, XFS_ICSB_FDBLK_CNTR_REENABLE(mp)))
                        goto out;
                break;
        default:
@@ -2054,32 +2327,39 @@ out:
                XFS_SB_UNLOCK(mp, s);
 }
 
-STATIC int
-xfs_icsb_modify_counters_int(
+int
+xfs_icsb_modify_counters(
        xfs_mount_t     *mp,
        xfs_sb_field_t  field,
-       int             delta,
-       int             rsvd,
-       int             flags)
+       int64_t         delta,
+       int             rsvd)
 {
        xfs_icsb_cnts_t *icsbp;
        long long       lcounter;       /* long counter for 64 bit fields */
-       int             cpu, s, locked = 0;
-       int             ret = 0, balance_done = 0;
+       int             cpu, ret = 0, s;
 
+       might_sleep();
 again:
        cpu = get_cpu();
-       icsbp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, cpu),
-       xfs_icsb_lock_cntr(icsbp);
+       icsbp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, cpu);
+
+       /*
+        * if the counter is disabled, go to slow path
+        */
        if (unlikely(xfs_icsb_counter_disabled(mp, field)))
                goto slow_path;
+       xfs_icsb_lock_cntr(icsbp);
+       if (unlikely(xfs_icsb_counter_disabled(mp, field))) {
+               xfs_icsb_unlock_cntr(icsbp);
+               goto slow_path;
+       }
 
        switch (field) {
        case XFS_SBS_ICOUNT:
                lcounter = icsbp->icsb_icount;
                lcounter += delta;
                if (unlikely(lcounter < 0))
-                       goto slow_path;
+                       goto balance_counter;
                icsbp->icsb_icount = lcounter;
                break;
 
@@ -2087,7 +2367,7 @@ again:
                lcounter = icsbp->icsb_ifree;
                lcounter += delta;
                if (unlikely(lcounter < 0))
-                       goto slow_path;
+                       goto balance_counter;
                icsbp->icsb_ifree = lcounter;
                break;
 
@@ -2097,7 +2377,7 @@ again:
                lcounter = icsbp->icsb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
                lcounter += delta;
                if (unlikely(lcounter < 0))
-                       goto slow_path;
+                       goto balance_counter;
                icsbp->icsb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
                break;
        default:
@@ -2106,72 +2386,78 @@ again:
        }
        xfs_icsb_unlock_cntr(icsbp);
        put_cpu();
-       if (locked)
-               XFS_SB_UNLOCK(mp, s);
        return 0;
 
-       /*
-        * The slow path needs to be run with the SBLOCK
-        * held so that we prevent other threads from
-        * attempting to run this path at the same time.
-        * this provides exclusion for the balancing code,
-        * and exclusive fallback if the balance does not
-        * provide enough resources to continue in an unlocked
-        * manner.
-        */
 slow_path:
-       xfs_icsb_unlock_cntr(icsbp);
        put_cpu();
 
-       /* need to hold superblock incase we need
-        * to disable a counter */
-       if (!(flags & XFS_ICSB_SB_LOCKED)) {
-               s = XFS_SB_LOCK(mp);
-               locked = 1;
-               flags |= XFS_ICSB_SB_LOCKED;
-       }
-       if (!balance_done) {
-               xfs_icsb_balance_counter(mp, field, flags);
-               balance_done = 1;
+       /*
+        * serialise with a mutex so we don't burn lots of cpu on
+        * the superblock lock. We still need to hold the superblock
+        * lock, however, when we modify the global structures.
+        */
+       xfs_icsb_lock(mp);
+
+       /*
+        * Now running atomically.
+        *
+        * If the counter is enabled, someone has beaten us to rebalancing.
+        * Drop the lock and try again in the fast path....
+        */
+       if (!(xfs_icsb_counter_disabled(mp, field))) {
+               xfs_icsb_unlock(mp);
                goto again;
-       } else {
-               /*
-                * we might not have enough on this local
-                * cpu to allocate for a bulk request.
-                * We need to drain this field from all CPUs
-                * and disable the counter fastpath
-                */
-               xfs_icsb_disable_counter(mp, field);
        }
 
+       /*
+        * The counter is currently disabled. Because we are
+        * running atomically here, we know a rebalance cannot
+        * be in progress. Hence we can go straight to operating
+        * on the global superblock. We do not call xfs_mod_incore_sb()
+        * here even though we need to get the SB_LOCK. Doing so
+        * will cause us to re-enter this function and deadlock.
+        * Hence we get the SB_LOCK ourselves and then call
+        * xfs_mod_incore_sb_unlocked() as the unlocked path operates
+        * directly on the global counters.
+        */
+       s = XFS_SB_LOCK(mp);
        ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
+       XFS_SB_UNLOCK(mp, s);
 
-       if (locked)
-               XFS_SB_UNLOCK(mp, s);
+       /*
+        * Now that we've modified the global superblock, we
+        * may be able to re-enable the distributed counters
+        * (e.g. lots of space just got freed). After that
+        * we are done.
+        */
+       if (ret != ENOSPC)
+               xfs_icsb_balance_counter(mp, field, 0, 0);
+       xfs_icsb_unlock(mp);
        return ret;
-}
 
-STATIC int
-xfs_icsb_modify_counters(
-       xfs_mount_t     *mp,
-       xfs_sb_field_t  field,
-       int             delta,
-       int             rsvd)
-{
-       return xfs_icsb_modify_counters_int(mp, field, delta, rsvd, 0);
-}
+balance_counter:
+       xfs_icsb_unlock_cntr(icsbp);
+       put_cpu();
 
-/*
- * Called when superblock is already locked
- */
-STATIC int
-xfs_icsb_modify_counters_locked(
-       xfs_mount_t     *mp,
-       xfs_sb_field_t  field,
-       int             delta,
-       int             rsvd)
-{
-       return xfs_icsb_modify_counters_int(mp, field, delta,
-                                               rsvd, XFS_ICSB_SB_LOCKED);
+       /*
+        * We may have multiple threads here if multiple per-cpu
+        * counters run dry at the same time. This will mean we can
+        * do more balances than strictly necessary but it is not
+        * the common slowpath case.
+        */
+       xfs_icsb_lock(mp);
+
+       /*
+        * running atomically.
+        *
+        * This will leave the counter in the correct state for future
+        * accesses. After the rebalance, we simply try again and our retry
+        * will either succeed through the fast path or slow path without
+        * another balance operation being required.
+        */
+       xfs_icsb_balance_counter(mp, field, 0, delta);
+       xfs_icsb_unlock(mp);
+       goto again;
 }
+
 #endif