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>

fs/xfs/Makefile

@@ -79,6 +79,7 @@ xfs-y				+= xfs_alloc.o \
 				   xfs_inode_fork.o \
 				   xfs_inode_buf.o \
 				   xfs_log_recover.o \
+				   xfs_log_rlimit.o \
 				   xfs_sb.o \
 				   xfs_symlink_remote.o \
 				   xfs_trans_resv.o

fs/xfs/xfs_log_format.h

@@ -19,6 +19,7 @@
 #define __XFS_LOG_FORMAT_H__
 
 struct xfs_mount;
+struct xfs_trans_res;
 
 /*
  * On-disk Log Format definitions.
@@ -51,6 +52,9 @@ typedef __uint32_t xlog_tid_t;
 
 #define XLOG_HEADER_SIZE	512
 
+/* Minimum number of transactions that must fit in the log (defined by mkfs) */
+#define XFS_MIN_LOG_FACTOR	3
+
 #define XLOG_REC_SHIFT(log) \
 	BTOBB(1 << (xfs_sb_version_haslogv2(&log->l_mp->m_sb) ? \
 	 XLOG_MAX_RECORD_BSHIFT : XLOG_BIG_RECORD_BSHIFT))
@@ -135,7 +139,6 @@ typedef struct xlog_op_header {
 	__u16	   oh_res2;	/* 32 bit align			:  2 b */
 } xlog_op_header_t;
 
-
 /* valid values for h_fmt */
 #define XLOG_FMT_UNKNOWN  0
 #define XLOG_FMT_LINUX_LE 1
@@ -837,5 +840,7 @@ struct xfs_icreate_log {
 };
 
 int	xfs_log_calc_unit_res(struct xfs_mount *mp, int unit_bytes);
+int	xfs_log_calc_minimum_size(struct xfs_mount *);
+
 
 #endif /* __XFS_LOG_FORMAT_H__ */

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);
+}