xfs: Add xfs_log_rlimit.c

Add source files for xfs_log_rlimit.c The new file is used for log
size calculations and validation shared with userspace.

[dchinner: xfs_log_calc_max_attrsetm_res() does not modify the
tr_attrsetm reservation, just calculates the maximum. ]

[dchinner: rework loop in xfs_log_get_max_trans_res() ]

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 145 insertions, 0 deletions

diff --git a/fs/xfs/xfs_log_rlimit.c b/fs/xfs/xfs_log_rlimit.c
new file mode 100644
index 000000000000..6b17ef4a061b
--- /dev/null
+++ b/fs/xfs/xfs_log_rlimit.c
@@ -0,0 +1,145 @@
+/*
+ * Copyright (c) 2013 Jie Liu.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_ag.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_trans_space.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_inode.h"
+#include "xfs_da_btree.h"
+#include "xfs_attr_leaf.h"
+
+/*
+ * Calculate the maximum length in bytes that would be required for a local
+ * attribute value as large attributes out of line are not logged.
+ */
+STATIC int
+xfs_log_calc_max_attrsetm_res(
+        struct xfs_mount        *mp)
+{
+        int                     size;
+        int                     nblks;
+
+        size = xfs_attr_leaf_entsize_local_max(mp->m_sb.sb_blocksize) -
+               MAXNAMELEN - 1;
+        nblks = XFS_DAENTER_SPACE_RES(mp, XFS_ATTR_FORK);
+        nblks += XFS_B_TO_FSB(mp, size);
+        nblks += XFS_NEXTENTADD_SPACE_RES(mp, size, XFS_ATTR_FORK);
+
+        return  M_RES(mp)->tr_attrsetm.tr_logres +
+                M_RES(mp)->tr_attrsetrt.tr_logres * nblks;
+}
+
+/*
+ * Iterate over the log space reservation table to figure out and return
+ * the maximum one in terms of the pre-calculated values which were done
+ * at mount time.
+ */
+STATIC void
+xfs_log_get_max_trans_res(
+        struct xfs_mount        *mp,
+        struct xfs_trans_res    *max_resp)
+{
+        struct xfs_trans_res    *resp;
+        struct xfs_trans_res    *end_resp;
+        int                     log_space = 0;
+        int                     attr_space;
+
+        attr_space = xfs_log_calc_max_attrsetm_res(mp);
+
+        resp = (struct xfs_trans_res *)M_RES(mp);
+        end_resp = (struct xfs_trans_res *)(M_RES(mp) + 1);
+        for (; resp < end_resp; resp++) {
+                int             tmp = resp->tr_logcount > 1 ?
+                                      resp->tr_logres * resp->tr_logcount :
+                                      resp->tr_logres;
+                if (log_space < tmp) {
+                        log_space = tmp;
+                        *max_resp = *resp;              /* struct copy */
+                }
+        }
+
+        if (attr_space > log_space) {
+                *max_resp = M_RES(mp)->tr_attrsetm;     /* struct copy */
+                max_resp->tr_logres = attr_space;
+        }
+}
+
+/*
+ * Calculate the minimum valid log size for the given superblock configuration.
+ * Used to calculate the minimum log size at mkfs time, and to determine if
+ * the log is large enough or not at mount time. Returns the minimum size in
+ * filesystem block size units.
+ */
+int
+xfs_log_calc_minimum_size(
+        struct xfs_mount        *mp)
+{
+        struct xfs_trans_res    tres = {0};
+        int                     max_logres;
+        int                     min_logblks = 0;
+        int                     lsunit = 0;
+
+        xfs_log_get_max_trans_res(mp, &tres);
+
+        max_logres = xfs_log_calc_unit_res(mp, tres.tr_logres);
+        if (tres.tr_logcount > 1)
+                max_logres *= tres.tr_logcount;
+
+        if (xfs_sb_version_haslogv2(&mp->m_sb) && mp->m_sb.sb_logsunit > 1)
+                lsunit = BTOBB(mp->m_sb.sb_logsunit);
+
+        /*
+         * Two factors should be taken into account for calculating the minimum
+         * log space.
+         * 1) The fundamental limitation is that no single transaction can be
+         *    larger than half size of the log.
+         *
+         *    From mkfs.xfs, this is considered by the XFS_MIN_LOG_FACTOR
+         *    define, which is set to 3. That means we can definitely fit
+         *    maximally sized 2 transactions in the log. We'll use this same
+         *    value here.
+         *
+         * 2) If the lsunit option is specified, a transaction requires 2 LSU
+         *    for the reservation because there are two log writes that can
+         *    require padding - the transaction data and the commit record which
+         *    are written separately and both can require padding to the LSU.
+         *    Consider that we can have an active CIL reservation holding 2*LSU,
+         *    but the CIL is not over a push threshold, in this case, if we
+         *    don't have enough log space for at one new transaction, which
+         *    includes another 2*LSU in the reservation, we will run into dead
+         *    loop situation in log space grant procedure. i.e.
+         *    xlog_grant_head_wait().
+         *
+         *    Hence the log size needs to be able to contain two maximally sized
+         *    and padded transactions, which is (2 * (2 * LSU + maxlres)).
+         *
+         * Also, the log size should be a multiple of the log stripe unit, round
+         * it up to lsunit boundary if lsunit is specified.
+         */
+        if (lsunit)
+                min_logblks = roundup(BTOBB(max_logres), lsunit) + 2 * lsunit;
+        else
+                min_logblks = BTOBB(max_logres) + 2 * BBSIZE;
+        min_logblks *= XFS_MIN_LOG_FACTOR;
+        return XFS_BB_TO_FSB(mp, min_logblks);
+}