fs/jfs: TRIM support for JFS Filesystem

This patch adds support for the two linux interfaces of the discard/TRIM command for SSD devices and sparse/thinly-provisioned LUNs.

Quoted 2 lines · Tino Reichardt

Quoted 2 lines

This patch adds support for the two linux interfaces of the discard/TRIM command for SSD devices and sparse/thinly-provisioned LUNs.

Fixed a problem when setting minlen in jfs_ioc_trim().

Signed-off-by Tino Reichardt <[email protected]>

-- regards, TR

jfs-trim-2012-07-28.diff

diff -X exclude -urpN linux-git/Documentation/filesystems/jfs.txt linux_jfs-trim/Documentation/filesystems/jfs.txt

Documentation/filesystems/jfs.txt +1 -1

@@ -3,6 +3,7 @@ IBM's Journaled File System (JFS) for Li
 JFS Homepage:  http://jfs.sourceforge.net/
 
 The following mount options are supported:
+(*) == default
 
 iocharset=name	Character set to use for converting from Unicode to
 		ASCII.  The default is to do no conversion.  Use

@@ -21,12 +22,12 @@ nointegrity	Do not write to the journal.
 		from backup media.  The integrity of the volume is not
 		guaranteed if the system abnormally abends.
 
-integrity	Default.  Commit metadata changes to the journal.  Use this

Documentation/filesystems/jfs.txt +3 -0

@@ -35,6 +36,18 @@ umask=value	Override on-disk umask with
 		directories, the execute bit will be set if the corresponding
 		read bit is set.
 
+discard=minlen	This enables/disables the use of discard/TRIM commands.
+discard		The discard/TRIM commands are sent to the underlying
+nodiscard(*)	block device when blocks are freed. This is useful for SSD

Documentation/filesystems/jfs.txt +0 -0

 The JFS mailing list can be subscribed to by using the link labeled

diff -X exclude -urpN linux-git/fs/jfs/Makefile linux_jfs-trim/fs/jfs/Makefile

fs/jfs/Makefile +1 -1

@@ -6,7 +6,7 @@ obj-$(CONFIG_JFS_FS) += jfs.o
 
 jfs-y    := super.o file.o inode.o namei.o jfs_mount.o jfs_umount.o \
 	    jfs_xtree.o jfs_imap.o jfs_debug.o jfs_dmap.o \
-	    jfs_unicode.o jfs_dtree.o jfs_inode.o \
+	    jfs_unicode.o jfs_dtree.o jfs_inode.o jfs_discard.o \
 	    jfs_extent.o symlink.o jfs_metapage.o \
 	    jfs_logmgr.o jfs_txnmgr.o jfs_uniupr.o \
 	    resize.o xattr.o ioctl.o

diff -X exclude -urpN linux-git/fs/jfs/ioctl.c linux_jfs-trim/fs/jfs/ioctl.c

fs/jfs/ioctl.c +42 -1

@@ -11,13 +11,17 @@
 #include <linux/mount.h>
 #include <linux/time.h>
 #include <linux/sched.h>
+#include <linux/blkdev.h>
 #include <asm/current.h>
 #include <asm/uaccess.h>
 
+#include "jfs_filsys.h"
+#include "jfs_debug.h"
 #include "jfs_incore.h"
 #include "jfs_dinode.h"
 #include "jfs_inode.h"
-
+#include "jfs_dmap.h"
+#include "jfs_discard.h"
 
 static struct {
 	long jfs_flag;

@@ -123,6 +127,40 @@ setflags_out:
 		mnt_drop_write_file(filp);
 		return err;
 	}
+
+	case FITRIM:
+	{
+		struct super_block *sb = inode->i_sb;
+		struct request_queue *q = bdev_get_queue(sb->s_bdev);
+		struct fstrim_range range;
+		s64 ret = 0;
+
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+
+		if (!blk_queue_discard(q)) {
+			jfs_warn("FITRIM not supported on device");
+			return -EOPNOTSUPP;
+		}
+
+		if (copy_from_user(&range, (struct fstrim_range __user *)arg,
+		    sizeof(range)))
+			return -EFAULT;
+
+		range.minlen = max((unsigned int)range.minlen,
+				   q->limits.discard_granularity);
+
+		ret = jfs_ioc_trim(inode, &range);
+		if (ret < 0)
+			return ret;
+
+		if (copy_to_user((struct fstrim_range __user *)arg, &range,
+		    sizeof(range)))
+			return -EFAULT;
+
+		return 0;
+	}
+
 	default:
 		return -ENOTTY;
 	}

@@ -142,6 +180,9 @@ long jfs_compat_ioctl(struct file *filp,
 	case JFS_IOC_SETFLAGS32:
 		cmd = JFS_IOC_SETFLAGS;
 		break;
+	case FITRIM:
+		cmd = FITRIM;
+		break;
 	}
 	return jfs_ioctl(filp, cmd, arg);
 }

diff -X exclude -urpN linux-git/fs/jfs/jfs_discard.c linux_jfs-trim/fs/jfs/jfs_discard.c

fs/jfs/jfs_discard.c +17 -0

@@ -0,0 +1,119 @@
+/*
+ *   Copyright (C) Tino Reichardt, 2012
+ *
+ *   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; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will 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 to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */

fs/jfs/jfs_discard.c +26 -0

+
+
+/*
+ * NAME:	jfs_issue_discard()
+ *
+ * FUNCTION:	TRIM the specified block range on device, if supported
+ *
+ * PARAMETERS:
+ *	ip	- pointer to in-core inode
+ *	blkno	- starting block number to be trimmed (0..N)
+ *	nblocks	- number of blocks to be trimmed
+ *
+ * RETURN VALUES:
+ *	none
+ *
+ * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
+ */
+void jfs_issue_discard(struct inode *ip, u64 blkno, u64 nblocks)
+{
+	struct super_block *sb = ip->i_sb;
+	int r = 0;
+
+	r = sb_issue_discard(sb, blkno, nblocks, GFP_NOFS, 0);
+	if (unlikely(r != 0)) {
+		printk(KERN_ERR "JFS: sb_issue_discard"
+			"(%p, %llu, %llu, GFP_NOFS, 0) = %d => failure!\n", sb,

fs/jfs/jfs_discard.c +56 -0

+
+	return;
+}
+
+/*
+ * NAME:	jfs_ioc_trim()
+ *
+ * FUNCTION:	attempt to discard (TRIM) all free blocks from the
+ *              filesystem.
+ *
+ * PARAMETERS:
+ *	ip	- pointer to in-core inode;
+ *	range	- the range, given by user space
+ *
+ * RETURN VALUES:
+ *	0	- success
+ *	-EIO	- i/o error
+ */
+int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range)
+{
+	struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
+	struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
+	struct super_block *sb = ipbmap->i_sb;
+	int agno, agno_end;
+	s64 start, end, minlen;
+	u64 trimmed = 0;
+
+	/**
+	 * convert byte values to block size of filesystem:
+	 * start:	First Byte to trim
+	 * len:		number of Bytes to trim from start
+	 * minlen:	minimum extent length in Bytes
+	 */
+	start = range->start >> sb->s_blocksize_bits;
+	if (start < 0)
+		start = 0;
+	end = start + (range->len >> sb->s_blocksize_bits) - 1;
+	if (end >= bmp->db_mapsize)
+		end = bmp->db_mapsize - 1;
+	minlen = range->minlen >> sb->s_blocksize_bits;
+	if (minlen <= 0)
+		minlen = 1;
+
+	/**
+	 * we trim all ag's within the range
+	 */
+	agno = BLKTOAG(start, JFS_SBI(ip->i_sb));
+	agno_end = BLKTOAG(end, JFS_SBI(ip->i_sb));
+	while (agno <= agno_end) {
+		trimmed += dbDiscardAG(ip, agno, minlen);
+		agno++;
+	}
+	range->len = trimmed << sb->s_blocksize_bits;
+
+	return 0;
+}

diff -X exclude -urpN linux-git/fs/jfs/jfs_discard.h linux_jfs-trim/fs/jfs/jfs_discard.h

fs/jfs/jfs_discard.h +26 -0

@@ -0,0 +1,26 @@
+/*
+ *   Copyright (C) Tino Reichardt, 2012
+ *
+ *   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; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will 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 to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+#ifndef	_H_JFS_DISCARD
+#define _H_JFS_DISCARD
+
+struct fstrim_range;
+
+extern void jfs_issue_discard(struct inode *ip, u64 blkno, u64 nblocks);
+extern int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range);
+
+#endif /* _H_JFS_DISCARD */

diff -X exclude -urpN linux-git/fs/jfs/jfs_dmap.c linux_jfs-trim/fs/jfs/jfs_dmap.c

fs/jfs/jfs_dmap.c +12 -4

@@ -1,5 +1,6 @@
 /*
  *   Copyright (C) International Business Machines Corp., 2000-2004
+ *   Portions Copyright (C) Tino Reichardt, 2012
  *
  *   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

@@ -25,6 +26,7 @@
 #include "jfs_lock.h"
 #include "jfs_metapage.h"
 #include "jfs_debug.h"
+#include "jfs_discard.h"
 
 /*
  *	SERIALIZATION of the Block Allocation Map.

@@ -104,7 +106,6 @@ static int dbFreeBits(struct bmap * bmp,
 static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
 		      int nblocks);
 static int dbMaxBud(u8 * cp);
-s64 dbMapFileSizeToMapSize(struct inode *ipbmap);
 static int blkstol2(s64 nb);
 
 static int cntlz(u32 value);

@@ -145,7 +146,6 @@ static const s8 budtab[256] = {
 	2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, -1
 };
 
-
 /*
  * NAME:	dbMount()
  *

@@ -310,7 +310,6 @@ int dbSync(struct inode *ipbmap)
 	return (0);
 }
 
-
 /*
  * NAME:	dbFree()
  *

@@ -337,6 +336,7 @@ int dbFree(struct inode *ip, s64 blkno,
 	s64 lblkno, rem;
 	struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
 	struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
+	struct super_block *sb = ipbmap->i_sb;
 
 	IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
 

@@ -351,6 +351,15 @@ int dbFree(struct inode *ip, s64 blkno,
 		return -EIO;
 	}
 
+	/**
+	 * TRIM the blocks, when mounted with discard option
+	 */
+	if (JFS_SBI(sb)->flag & JFS_DISCARD) {
+		if (JFS_SBI(sb)->minblks_trim <= nblocks) {
+			jfs_issue_discard(ipbmap, blkno, nblocks);
+		}
+	}
+
 	/*
 	 * free the blocks a dmap at a time.
 	 */

@@ -1095,7 +1104,6 @@ static int dbExtend(struct inode *ip, s6
 		/* we were not successful */
 		release_metapage(mp);
 
-
 	return (rc);
 }
 

fs/jfs/jfs_dmap.c +26 -0

+ * 		- reading / writing the fs is possible most time, even on trimming
+ *
+ * 		downside:
+ * 		- we write two times to the dmapctl and dmap pages
+ * 		- but for me, this seems the best way, better ideas?
+ * 		/TR 2012
+ *
+ * PARAMETERS:
+ *	ip	- pointer to in-core inode
+ *	agno	- ag to trim
+ *	minlen	- minimum value of contiguous blocks
+ *
+ * RETURN VALUES:
+ *	s64	- actual number of blocks trimmed
+ */
+s64 dbDiscardAG(struct inode *ip, int agno, s64 minlen)
+{
+	struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
+	struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
+	s64 nblocks, blkno;
+	u64 trimmed = 0;
+	int rc, l2nb;
+	struct super_block *sb = ipbmap->i_sb;
+
+	struct range2trim {
+		u64 blkno;

fs/jfs/jfs_dmap.c +4 -0

+	nblocks = bmp->db_agfree[agno];
+	totrim = kmalloc(sizeof(struct range2trim) * range_cnt, GFP_NOFS);
+	if (totrim == NULL) {
+		jfs_error(bmp->db_ipbmap->i_sb,

fs/jfs/jfs_dmap.c +29 -0

+		rc = dbAllocAG(bmp, agno, nblocks, l2nb, &blkno);
+		if (rc == 0) {
+			tt->blkno = blkno;
+			tt->nblocks = nblocks;
+			tt++; count++;
+
+#ifdef JFS_DEBUG_TRIM
+		printk(KERN_INFO "JFS: agno=%d/%d, blkno:%ld, nblocks=%ld\n",
+			agno+1, bmp->db_numag, (long int)blkno,
+			(long int)nblocks);
+#endif
+
+			/* the whole ag is free, trim now */
+			if (bmp->db_agfree[agno] == 0)
+				break;
+
+			/* give a hint for the next while */
+			nblocks = bmp->db_agfree[agno];
+			continue;
+		} else if (rc == -ENOSPC) {
+			/* search for next smaller log2 block */
+			l2nb = BLKSTOL2(nblocks) - 1;
+			nblocks = 1 << l2nb;
+		} else {
+			/* Trim any already-allocated blocks */
+			printk(KERN_ERR "JFS: dbDiscardAG: -EIO\n");
+			break;
+		}
+

fs/jfs/jfs_dmap.c +11 -0

+			jfs_issue_discard(ip, tt->blkno, tt->nblocks);
+		}
+		dbFree(ip, tt->blkno, tt->nblocks);
+		trimmed += tt->nblocks;
+	}
+	kfree(totrim);
+
+	return trimmed;
+}
+
+/*
  * NAME:	dbFindCtl()
  *
  * FUNCTION:	starting at a specified dmap control page level and block

diff -X exclude -urpN linux-git/fs/jfs/jfs_dmap.h linux_jfs-trim/fs/jfs/jfs_dmap.h

fs/jfs/jfs_dmap.h +2 -0

@@ -311,4 +311,6 @@ extern int dbAllocBottomUp(struct inode
 extern int dbExtendFS(struct inode *ipbmap, s64 blkno, s64 nblocks);
 extern void dbFinalizeBmap(struct inode *ipbmap);
 extern s64 dbMapFileSizeToMapSize(struct inode *ipbmap);
+extern s64 dbDiscardAG(struct inode *ip, int agno, s64 minlen);
+
 #endif				/* _H_JFS_DMAP */

diff -X exclude -urpN linux-git/fs/jfs/jfs_filsys.h linux_jfs-trim/fs/jfs/jfs_filsys.h

fs/jfs/jfs_filsys.h +3 -0

@@ -45,6 +45,9 @@
 /* mount time flag to disable journaling to disk */
 #define JFS_NOINTEGRITY 0x00000040
 
+/* mount time flag to enable TRIM to ssd disks */
+#define JFS_DISCARD     0x00000080
+
 /* commit option */
 #define	JFS_COMMIT	0x00000f00	/* commit option mask */
 #define	JFS_GROUPCOMMIT	0x00000100	/* group (of 1) commit */

diff -X exclude -urpN linux-git/fs/jfs/jfs_incore.h linux_jfs-trim/fs/jfs/jfs_incore.h

fs/jfs/jfs_incore.h +1 -0

@@ -195,6 +195,7 @@ struct jfs_sb_info {
 	uint		uid;		/* uid to override on-disk uid */
 	uint		gid;		/* gid to override on-disk gid */
 	uint		umask;		/* umask to override on-disk umask */
+	uint		minblks_trim;	/* minimum blocks, for online trim */
 };
 
 /* jfs_sb_info commit_state */

diff -X exclude -urpN linux-git/fs/jfs/super.c linux_jfs-trim/fs/jfs/super.c

fs/jfs/super.c +45 -1

@@ -33,6 +33,7 @@
 #include <linux/slab.h>
 #include <asm/uaccess.h>
 #include <linux/seq_file.h>
+#include <linux/blkdev.h>
 
 #include "jfs_incore.h"
 #include "jfs_filsys.h"

@@ -197,7 +198,8 @@ static void jfs_put_super(struct super_b
 enum {
 	Opt_integrity, Opt_nointegrity, Opt_iocharset, Opt_resize,
 	Opt_resize_nosize, Opt_errors, Opt_ignore, Opt_err, Opt_quota,
-	Opt_usrquota, Opt_grpquota, Opt_uid, Opt_gid, Opt_umask
+	Opt_usrquota, Opt_grpquota, Opt_uid, Opt_gid, Opt_umask,
+	Opt_discard, Opt_nodiscard, Opt_discard_minblk
 };
 
 static const match_table_t tokens = {

@@ -214,6 +216,9 @@ static const match_table_t tokens = {
 	{Opt_uid, "uid=%u"},
 	{Opt_gid, "gid=%u"},
 	{Opt_umask, "umask=%u"},
+	{Opt_discard, "discard"},
+	{Opt_nodiscard, "nodiscard"},
+	{Opt_discard_minblk, "discard=%u"},
 	{Opt_err, NULL}
 };
 

@@ -324,12 +329,14 @@ static int parse_options(char *options,
 			sbi->uid = simple_strtoul(uid, &uid, 0);
 			break;
 		}
+
 		case Opt_gid:
 		{
 			char *gid = args[0].from;
 			sbi->gid = simple_strtoul(gid, &gid, 0);
 			break;
 		}
+
 		case Opt_umask:
 		{
 			char *umask = args[0].from;

@@ -341,6 +348,43 @@ static int parse_options(char *options,
 			}
 			break;
 		}
+
+		case Opt_discard:
+		{
+			struct request_queue *q = bdev_get_queue(sb->s_bdev);
+			/* if set to 1, even copying files will cause
+			 * trimming :O
+			 * -> user has more control over the online trimming
+			 */
+			sbi->minblks_trim = 64;
+			if (blk_queue_discard(q)) {
+				*flag |= JFS_DISCARD;
+			} else {
+				printk(KERN_ERR "JFS: discard option "
+					"not supported on device\n");
+			}
+			break;
+		}
+
+		case Opt_nodiscard:
+			*flag &= ~JFS_DISCARD;
+			break;
+
+		case Opt_discard_minblk:
+		{
+			struct request_queue *q = bdev_get_queue(sb->s_bdev);
+			char *minblks_trim = args[0].from;
+			if (blk_queue_discard(q)) {
+				*flag |= JFS_DISCARD;
+				sbi->minblks_trim = simple_strtoull(
+					minblks_trim, &minblks_trim, 0);
+			} else {
+				printk(KERN_ERR "JFS: discard option "
+					"not supported on device\n");
+			}
+			break;
+		}
+
 		default:
 			printk("jfs: Unrecognized mount option \"%s\" "
 					" or missing value\n", p);

Quoted 4 lines · Tino Reichardt

Quoted 2 lines · Tino Reichardt

Quoted 2 lines

This patch adds support for the two linux interfaces of the discard/TRIM command for SSD devices and sparse/thinly-provisioned LUNs.

Fixed a problem when setting minlen in jfs_ioc_trim().

Overall, I approve of this. checkpatch reports some formatting problems:
whitespace, long lines, etc. You could probably ignore the warning changing printk to pr_err or pr_info, since none of the other JFS code does that.

Other comments are inline below. Pending additional input, I can push a cleaned-up patch upstream.

Quoted 2 lines

Signed-off-by Tino Reichardt <[email protected]>

Acked-by Dave Kleikamp <[email protected]>

Quoted 10 lines

...

errors=continue Keep going on a filesystem error.

(quoted diff) +1 -1

-errors=remount-ro	Default. Remount the filesystem read-only on an error.
+errors=remount-ro(*)	Default. Remount the filesystem read-only on an error.
 errors=panic		Panic and halt the machine if an error occurs.

Quoted 1 line

uid=value Override on-disk uid with specified value

I don't mind the (*) indicating the defaults. This would be consistent with some of the other files in this directory. But we should then remove the word "Default", which becomes redundant.

Quoted 5 lines

(quoted diff) +0 -0

@@ -35,6 +36,18 @@ umask=value	Override on-disk umask with
 		directories, the execute bit will be set if the corresponding
 		read bit is set.
 

Review umask=value Override on-disk umask with · line 51

Quoted 13 lines

(quoted diff) +12 -0

+discard=minlen	This enables/disables the use of discard/TRIM commands.
+discard		The discard/TRIM commands are sent to the underlying
+nodiscard(*)	block device when blocks are freed. This is useful for SSD
+		devices and sparse/thinly-provisioned LUNs.  The FITRIM ioctl
+		command is also available together with the nodiscard option.
+		The value of minlen specifies the minimum blockcount, when
+		a TRIM command to the block device is considered usefull.
+		When no value is given to the discard option, it defaults to
+		64 blocks, which means 256KiB in JFS.
+		The minlen value of discard overrides the minlen value given
+		on an FITRIM ioctl().
+
 Please send bugs, comments, cards and letters to [email protected].

Oops, not a problem with your patch. I still have my old email address here. I need to remove that.

Quoted 28 lines

diff -X exclude -urpN linux-git/fs/jfs/jfs_discard.c linux_jfs-trim/fs/jfs/jfs_discard.c

fs/jfs/jfs_discard.c +23 -0

@@ -0,0 +1,119 @@
+/*
+ *   Copyright (C) Tino Reichardt, 2012
+ *
+ *   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; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will 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 to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+
+#include "jfs_incore.h"

fs/jfs/jfs_discard.c line 27

Quoted 4 lines

fs/jfs/jfs_discard.c +4 -0

+#include "jfs_superblock.h"
+#include "jfs_dmap.h"
+#include "jfs_lock.h"
+#include "jfs_debug.h"

Should include "jfs_discard.h" to ensure that the declarations and definitions of these functions stay in sync. That would also clean up a sparse warning.

Quoted 32 lines

fs/jfs/jfs_discard.c +31 -0

+
+
+/*
+ * NAME:	jfs_issue_discard()
+ *
+ * FUNCTION:	TRIM the specified block range on device, if supported
+ *
+ * PARAMETERS:
+ *	ip	- pointer to in-core inode
+ *	blkno	- starting block number to be trimmed (0..N)
+ *	nblocks	- number of blocks to be trimmed
+ *
+ * RETURN VALUES:
+ *	none
+ *
+ * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
+ */
+void jfs_issue_discard(struct inode *ip, u64 blkno, u64 nblocks)
+{
+	struct super_block *sb = ip->i_sb;
+	int r = 0;
+
+	r = sb_issue_discard(sb, blkno, nblocks, GFP_NOFS, 0);
+	if (unlikely(r != 0)) {
+		printk(KERN_ERR "JFS: sb_issue_discard"
+			"(%p, %llu, %llu, GFP_NOFS, 0) = %d => failure!\n", sb,
+			(unsigned long long)blkno,
+			(unsigned long long)nblocks, r);
+	}
+
+#ifdef JFS_DEBUG_TRIM

fs/jfs/jfs_discard.c line 63

Quoted 5 lines

fs/jfs/jfs_discard.c +5 -0

+	printk(KERN_INFO "JFS: sb_issue_discard"
+		"(%p, %llu, %llu, GFP_NOFS, 0) = %d\n", sb,
+		(unsigned long long)blkno,
+		(unsigned long long)nblocks, r);
+#endif

Okay for now, but probably should drop the debug stuff before merging into mainline.

Quoted 8 lines

/*
+ * NAME: dbDiscardAG()
+ *
+ * FUNCTION: attempt to discard (TRIM) all free blocks of specific AG
+ *
+ * algorithm:
+ * 1) allocate blocks, as large as possible and save them

while holding IWRITE_LOCK on ipbmap

Quoted 5 lines

+ * 2) trim all these saved block/length values
+ * 3) mark the blocks free again
+ *
+ * benefit:
+ * - we work only on one ag at some time, which is fully blocked

maybe say "we work only on one ag at some time,
minimizing how long we need to lock ipbmap"
- no lock is held while discarding the blocks

Quoted 32 lines

+ * - reading / writing the fs is possible most time, even on trimming
+ *
+ * downside:
+ * - we write two times to the dmapctl and dmap pages
+ * - but for me, this seems the best way, better ideas?
+ * /TR 2012
+ *
+ * PARAMETERS:
+ * ip - pointer to in-core inode
+ * agno - ag to trim
+ * minlen - minimum value of contiguous blocks
+ *
+ * RETURN VALUES:
+ * s64 - actual number of blocks trimmed
+ */

fs/jfs/jfs_discard.c +17 -0

+s64 dbDiscardAG(struct inode *ip, int agno, s64 minlen)
+{
+	struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
+	struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
+	s64 nblocks, blkno;
+	u64 trimmed = 0;
+	int rc, l2nb;
+	struct super_block *sb = ipbmap->i_sb;
+
+	struct range2trim {
+		u64 blkno;
+		u64 nblocks;
+	} *totrim, *tt;
+
+	/* max blkno / nblocks pairs to trim */
+	int count = 0, range_cnt = 32 * 1024;
+

fs/jfs/jfs_discard.c

Quoted 4 lines

fs/jfs/jfs_discard.c +4 -0

+	/* prevent others from writing new stuff here, while trimming */
+	IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
+
+	/* worst value: each free block gets an entry */

This comment is no longer accurate or necessary, as you only allocate range_cnt elements. It could be limited to min(range_cnt, nblocks/minlen+1), but that's probably not too large an allocation for modern hardware.

Quoted 5 lines

fs/jfs/jfs_discard.c +4 -0

+	nblocks = bmp->db_agfree[agno];
+	totrim = kmalloc(sizeof(struct range2trim) * range_cnt, GFP_NOFS);
+	if (totrim == NULL) {
+		jfs_error(bmp->db_ipbmap->i_sb,

fs/jfs/jfs_discard.c

Quoted 10 lines

fs/jfs/jfs_discard.c +10 -0

+			  "dbDiscardAG: no space for trim array");
+		IWRITE_UNLOCK(ipbmap);
+		return 0;
+	}
+
+	tt = totrim;
+	while (nblocks >= minlen) {
+		l2nb = BLKSTOL2(nblocks);
+
+		/* 0 = okay, -EIO = fatal, -ENOSPC -> block kleiner */

English comments please. :-) Maybe "try smaller block"

Quoted 36 lines

fs/jfs/jfs_discard.c +35 -0

+		rc = dbAllocAG(bmp, agno, nblocks, l2nb, &blkno);
+		if (rc == 0) {
+			tt->blkno = blkno;
+			tt->nblocks = nblocks;
+			tt++; count++;
+
+#ifdef JFS_DEBUG_TRIM
+		printk(KERN_INFO "JFS: agno=%d/%d, blkno:%ld, nblocks=%ld\n",
+			agno+1, bmp->db_numag, (long int)blkno,
+			(long int)nblocks);
+#endif
+
+			/* the whole ag is free, trim now */
+			if (bmp->db_agfree[agno] == 0)
+				break;
+
+			/* give a hint for the next while */
+			nblocks = bmp->db_agfree[agno];
+			continue;
+		} else if (rc == -ENOSPC) {
+			/* search for next smaller log2 block */
+			l2nb = BLKSTOL2(nblocks) - 1;
+			nblocks = 1 << l2nb;
+		} else {
+			/* Trim any already-allocated blocks */
+			printk(KERN_ERR "JFS: dbDiscardAG: -EIO\n");
+			break;
+		}
+
+		/* check, if our trim array is full */
+		if (unlikely(count >= range_cnt - 1))
+			break;
+	}
+	IWRITE_UNLOCK(ipbmap);
+

fs/jfs/jfs_discard.c

Quoted 4 lines

fs/jfs/jfs_discard.c +4 -0

+	tt->nblocks = 0; /* mark the current end */
+	for (tt = totrim; tt->nblocks != 0; tt++) {
+		if (!(JFS_SBI(sb)->flag & JFS_DISCARD)) {
+			/* not needed, when online discard is used */

Why enter the function at all if JFS_DISCARD is set? But is this really true? Removing files or file fragments that are smaller than minblks_trim will fail to discard them dynamically.

Quoted 10 lines · Dave Kleikamp

fs/jfs/jfs_dmap.c static int dbAllocAny(struct bmap * bmp,

Quoted 4 lines · Tino Reichardt

fs/jfs/jfs_dmap.c +4 -0

+	tt->nblocks = 0; /* mark the current end */
+	for (tt = totrim; tt->nblocks != 0; tt++) {
+		if (!(JFS_SBI(sb)->flag & JFS_DISCARD)) {
+			/* not needed, when online discard is used */

Why enter the function at all if JFS_DISCARD is set? But is this really true? Removing files or file fragments that are smaller than minblks_trim will fail to discard them dynamically.

The other FS can also trim via fstrim(8) when mounted with discard option :) It is important, that a user can discard all free blocks, even when mounting with discard option. The FS could also be mounted several times without discard option, and then there are some ranges, where the device isn't informed about these ranges. So the batched discard ioctl() is then the only way to change that.

The comment there was also a bit updated, here is it:

/* when mounted with online discard, dbFree() will
* call jfs_issue_discard() itself */

Quoted 5 lines · Dave Kleikamp

Quoted 4 lines · Tino Reichardt

Quoted 2 lines · Tino Reichardt

Quoted 2 lines

This patch adds support for the two linux interfaces of the discard/TRIM command for SSD devices and sparse/thinly-provisioned LUNs.

Fixed a problem when setting minlen in jfs_ioc_trim().

Quoted 6 lines · Dave Kleikamp

Quoted 5 lines · Tino Reichardt

Quoted 4 lines · Tino Reichardt

Quoted 2 lines

Quoted 2 lines

This patch adds support for the two linux interfaces of the discard/TRIM command for SSD devices and sparse/thinly-provisioned LUNs.

Fixed a problem when setting minlen in jfs_ioc_trim().

Oops, setting minlen in jfs_ioc_trim() was again wrong :/

I changed this
if (minlen < 0)

	minlen = 1;

to this:
if (minlen <= 0)

	minlen = 1;

This is important, since fstrim() sets it to zero.

Fully working patch is located here:
http://www.mcmilk.de/projects/jfs-trim/linux-tree/jfs-trim-2012-08-01_v2.diff

Signed-off-by Tino Reichardt <[email protected]>