1 files changed, 584 insertions, 51 deletions

diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
index 1d6f488ccae..2a869c35c36 100644
--- a/fs/nilfs2/sufile.c
+++ b/fs/nilfs2/sufile.c
@@ -30,10 +30,18 @@
 #include "mdt.h"
 #include "sufile.h"
 
-
+/**
+ * struct nilfs_sufile_info - on-memory private data of sufile
+ * @mi: on-memory private data of metadata file
+ * @ncleansegs: number of clean segments
+ * @allocmin: lower limit of allocatable segment range
+ * @allocmax: upper limit of allocatable segment range
+ */
 struct nilfs_sufile_info {
 	struct nilfs_mdt_info mi;
-	unsigned long ncleansegs;
+	unsigned long ncleansegs;/* number of clean segments */
+	__u64 allocmin;		/* lower limit of allocatable segment range */
+	__u64 allocmax;		/* upper limit of allocatable segment range */
 };
 
 static inline struct nilfs_sufile_info *NILFS_SUI(struct inode *sufile)
@@ -96,19 +104,26 @@ nilfs_sufile_get_segment_usage_block(struct inode *sufile, __u64 segnum,
 				   create, NULL, bhp);
 }
 
+static int nilfs_sufile_delete_segment_usage_block(struct inode *sufile,
+						   __u64 segnum)
+{
+	return nilfs_mdt_delete_block(sufile,
+				      nilfs_sufile_get_blkoff(sufile, segnum));
+}
+
 static void nilfs_sufile_mod_counter(struct buffer_head *header_bh,
 				     u64 ncleanadd, u64 ndirtyadd)
 {
 	struct nilfs_sufile_header *header;
 	void *kaddr;
 
-	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(header_bh->b_page);
 	header = kaddr + bh_offset(header_bh);
 	le64_add_cpu(&header->sh_ncleansegs, ncleanadd);
 	le64_add_cpu(&header->sh_ndirtysegs, ndirtyadd);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 
-	nilfs_mdt_mark_buffer_dirty(header_bh);
+	mark_buffer_dirty(header_bh);
 }
 
 /**
@@ -248,6 +263,35 @@ int nilfs_sufile_update(struct inode *sufile, __u64 segnum, int create,
 }
 
 /**
+ * nilfs_sufile_set_alloc_range - limit range of segment to be allocated
+ * @sufile: inode of segment usage file
+ * @start: minimum segment number of allocatable region (inclusive)
+ * @end: maximum segment number of allocatable region (inclusive)
+ *
+ * Return Value: On success, 0 is returned.  On error, one of the
+ * following negative error codes is returned.
+ *
+ * %-ERANGE - invalid segment region
+ */
+int nilfs_sufile_set_alloc_range(struct inode *sufile, __u64 start, __u64 end)
+{
+	struct nilfs_sufile_info *sui = NILFS_SUI(sufile);
+	__u64 nsegs;
+	int ret = -ERANGE;
+
+	down_write(&NILFS_MDT(sufile)->mi_sem);
+	nsegs = nilfs_sufile_get_nsegments(sufile);
+
+	if (start <= end && end < nsegs) {
+		sui->allocmin = start;
+		sui->allocmax = end;
+		ret = 0;
+	}
+	up_write(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
+
+/**
  * nilfs_sufile_alloc - allocate a segment
  * @sufile: inode of segment usage file
  * @segnump: pointer to segment number
@@ -269,37 +313,56 @@ int nilfs_sufile_alloc(struct inode *sufile, __u64 *segnump)
 	struct buffer_head *header_bh, *su_bh;
 	struct nilfs_sufile_header *header;
 	struct nilfs_segment_usage *su;
+	struct nilfs_sufile_info *sui = NILFS_SUI(sufile);
 	size_t susz = NILFS_MDT(sufile)->mi_entry_size;
 	__u64 segnum, maxsegnum, last_alloc;
 	void *kaddr;
-	unsigned long nsegments, ncleansegs, nsus;
-	int ret, i, j;
+	unsigned long nsegments, ncleansegs, nsus, cnt;
+	int ret, j;
 
 	down_write(&NILFS_MDT(sufile)->mi_sem);
 
 	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
 	if (ret < 0)
 		goto out_sem;
-	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(header_bh->b_page);
 	header = kaddr + bh_offset(header_bh);
 	ncleansegs = le64_to_cpu(header->sh_ncleansegs);
 	last_alloc = le64_to_cpu(header->sh_last_alloc);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 
 	nsegments = nilfs_sufile_get_nsegments(sufile);
+	maxsegnum = sui->allocmax;
 	segnum = last_alloc + 1;
-	maxsegnum = nsegments - 1;
-	for (i = 0; i < nsegments; i += nsus) {
-		if (segnum >= nsegments) {
-			/* wrap around */
-			segnum = 0;
-			maxsegnum = last_alloc;
+	if (segnum < sui->allocmin || segnum > sui->allocmax)
+		segnum = sui->allocmin;
+
+	for (cnt = 0; cnt < nsegments; cnt += nsus) {
+		if (segnum > maxsegnum) {
+			if (cnt < sui->allocmax - sui->allocmin + 1) {
+				/*
+				 * wrap around in the limited region.
+				 * if allocation started from
+				 * sui->allocmin, this never happens.
+				 */
+				segnum = sui->allocmin;
+				maxsegnum = last_alloc;
+			} else if (segnum > sui->allocmin &&
+				   sui->allocmax + 1 < nsegments) {
+				segnum = sui->allocmax + 1;
+				maxsegnum = nsegments - 1;
+			} else if (sui->allocmin > 0)  {
+				segnum = 0;
+				maxsegnum = sui->allocmin - 1;
+			} else {
+				break; /* never happens */
+			}
 		}
 		ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 1,
 							   &su_bh);
 		if (ret < 0)
 			goto out_header;
-		kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+		kaddr = kmap_atomic(su_bh->b_page);
 		su = nilfs_sufile_block_get_segment_usage(
 			sufile, segnum, su_bh, kaddr);
 
@@ -310,25 +373,25 @@ int nilfs_sufile_alloc(struct inode *sufile, __u64 *segnump)
 				continue;
 			/* found a clean segment */
 			nilfs_segment_usage_set_dirty(su);
-			kunmap_atomic(kaddr, KM_USER0);
+			kunmap_atomic(kaddr);
 
-			kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+			kaddr = kmap_atomic(header_bh->b_page);
 			header = kaddr + bh_offset(header_bh);
 			le64_add_cpu(&header->sh_ncleansegs, -1);
 			le64_add_cpu(&header->sh_ndirtysegs, 1);
 			header->sh_last_alloc = cpu_to_le64(segnum);
-			kunmap_atomic(kaddr, KM_USER0);
+			kunmap_atomic(kaddr);
 
-			NILFS_SUI(sufile)->ncleansegs--;
-			nilfs_mdt_mark_buffer_dirty(header_bh);
-			nilfs_mdt_mark_buffer_dirty(su_bh);
+			sui->ncleansegs--;
+			mark_buffer_dirty(header_bh);
+			mark_buffer_dirty(su_bh);
 			nilfs_mdt_mark_dirty(sufile);
 			brelse(su_bh);
 			*segnump = segnum;
 			goto out_header;
 		}
 
-		kunmap_atomic(kaddr, KM_USER0);
+		kunmap_atomic(kaddr);
 		brelse(su_bh);
 	}
 
@@ -350,21 +413,21 @@ void nilfs_sufile_do_cancel_free(struct inode *sufile, __u64 segnum,
 	struct nilfs_segment_usage *su;
 	void *kaddr;
 
-	kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(su_bh->b_page);
 	su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
 	if (unlikely(!nilfs_segment_usage_clean(su))) {
 		printk(KERN_WARNING "%s: segment %llu must be clean\n",
 		       __func__, (unsigned long long)segnum);
-		kunmap_atomic(kaddr, KM_USER0);
+		kunmap_atomic(kaddr);
 		return;
 	}
 	nilfs_segment_usage_set_dirty(su);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 
 	nilfs_sufile_mod_counter(header_bh, -1, 1);
 	NILFS_SUI(sufile)->ncleansegs--;
 
-	nilfs_mdt_mark_buffer_dirty(su_bh);
+	mark_buffer_dirty(su_bh);
 	nilfs_mdt_mark_dirty(sufile);
 }
 
@@ -376,11 +439,11 @@ void nilfs_sufile_do_scrap(struct inode *sufile, __u64 segnum,
 	void *kaddr;
 	int clean, dirty;
 
-	kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(su_bh->b_page);
 	su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
 	if (su->su_flags == cpu_to_le32(1UL << NILFS_SEGMENT_USAGE_DIRTY) &&
 	    su->su_nblocks == cpu_to_le32(0)) {
-		kunmap_atomic(kaddr, KM_USER0);
+		kunmap_atomic(kaddr);
 		return;
 	}
 	clean = nilfs_segment_usage_clean(su);
@@ -390,12 +453,12 @@ void nilfs_sufile_do_scrap(struct inode *sufile, __u64 segnum,
 	su->su_lastmod = cpu_to_le64(0);
 	su->su_nblocks = cpu_to_le32(0);
 	su->su_flags = cpu_to_le32(1UL << NILFS_SEGMENT_USAGE_DIRTY);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 
 	nilfs_sufile_mod_counter(header_bh, clean ? (u64)-1 : 0, dirty ? 0 : 1);
 	NILFS_SUI(sufile)->ncleansegs -= clean;
 
-	nilfs_mdt_mark_buffer_dirty(su_bh);
+	mark_buffer_dirty(su_bh);
 	nilfs_mdt_mark_dirty(sufile);
 }
 
@@ -407,12 +470,12 @@ void nilfs_sufile_do_free(struct inode *sufile, __u64 segnum,
 	void *kaddr;
 	int sudirty;
 
-	kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(su_bh->b_page);
 	su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
 	if (nilfs_segment_usage_clean(su)) {
 		printk(KERN_WARNING "%s: segment %llu is already clean\n",
 		       __func__, (unsigned long long)segnum);
-		kunmap_atomic(kaddr, KM_USER0);
+		kunmap_atomic(kaddr);
 		return;
 	}
 	WARN_ON(nilfs_segment_usage_error(su));
@@ -420,8 +483,8 @@ void nilfs_sufile_do_free(struct inode *sufile, __u64 segnum,
 
 	sudirty = nilfs_segment_usage_dirty(su);
 	nilfs_segment_usage_set_clean(su);
-	kunmap_atomic(kaddr, KM_USER0);
-	nilfs_mdt_mark_buffer_dirty(su_bh);
+	kunmap_atomic(kaddr);
+	mark_buffer_dirty(su_bh);
 
 	nilfs_sufile_mod_counter(header_bh, 1, sudirty ? (u64)-1 : 0);
 	NILFS_SUI(sufile)->ncleansegs++;
@@ -441,7 +504,7 @@ int nilfs_sufile_mark_dirty(struct inode *sufile, __u64 segnum)
 
 	ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &bh);
 	if (!ret) {
-		nilfs_mdt_mark_buffer_dirty(bh);
+		mark_buffer_dirty(bh);
 		nilfs_mdt_mark_dirty(sufile);
 		brelse(bh);
 	}
@@ -468,15 +531,15 @@ int nilfs_sufile_set_segment_usage(struct inode *sufile, __u64 segnum,
 	if (ret < 0)
 		goto out_sem;
 
-	kaddr = kmap_atomic(bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(bh->b_page);
 	su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr);
 	WARN_ON(nilfs_segment_usage_error(su));
 	if (modtime)
 		su->su_lastmod = cpu_to_le64(modtime);
 	su->su_nblocks = cpu_to_le32(nblocks);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 
-	nilfs_mdt_mark_buffer_dirty(bh);
+	mark_buffer_dirty(bh);
 	nilfs_mdt_mark_dirty(sufile);
 	brelse(bh);
 
@@ -505,7 +568,7 @@ int nilfs_sufile_get_stat(struct inode *sufile, struct nilfs_sustat *sustat)
 {
 	struct buffer_head *header_bh;
 	struct nilfs_sufile_header *header;
-	struct the_nilfs *nilfs = NILFS_I_NILFS(sufile);
+	struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
 	void *kaddr;
 	int ret;
 
@@ -515,7 +578,7 @@ int nilfs_sufile_get_stat(struct inode *sufile, struct nilfs_sustat *sustat)
 	if (ret < 0)
 		goto out_sem;
 
-	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(header_bh->b_page);
 	header = kaddr + bh_offset(header_bh);
 	sustat->ss_nsegs = nilfs_sufile_get_nsegments(sufile);
 	sustat->ss_ncleansegs = le64_to_cpu(header->sh_ncleansegs);
@@ -525,7 +588,7 @@ int nilfs_sufile_get_stat(struct inode *sufile, struct nilfs_sustat *sustat)
 	spin_lock(&nilfs->ns_last_segment_lock);
 	sustat->ss_prot_seq = nilfs->ns_prot_seq;
 	spin_unlock(&nilfs->ns_last_segment_lock);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 	brelse(header_bh);
 
  out_sem:
@@ -541,22 +604,194 @@ void nilfs_sufile_do_set_error(struct inode *sufile, __u64 segnum,
 	void *kaddr;
 	int suclean;
 
-	kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(su_bh->b_page);
 	su = nilfs_sufile_block_get_segment_usage(sufile, segnum, su_bh, kaddr);
 	if (nilfs_segment_usage_error(su)) {
-		kunmap_atomic(kaddr, KM_USER0);
+		kunmap_atomic(kaddr);
 		return;
 	}
 	suclean = nilfs_segment_usage_clean(su);
 	nilfs_segment_usage_set_error(su);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 
 	if (suclean) {
 		nilfs_sufile_mod_counter(header_bh, -1, 0);
 		NILFS_SUI(sufile)->ncleansegs--;
 	}
-	nilfs_mdt_mark_buffer_dirty(su_bh);
+	mark_buffer_dirty(su_bh);
+	nilfs_mdt_mark_dirty(sufile);
+}
+
+/**
+  * nilfs_sufile_truncate_range - truncate range of segment array
+  * @sufile: inode of segment usage file
+  * @start: start segment number (inclusive)
+  * @end: end segment number (inclusive)
+  *
+  * Return Value: On success, 0 is returned.  On error, one of the
+  * following negative error codes is returned.
+  *
+  * %-EIO - I/O error.
+  *
+  * %-ENOMEM - Insufficient amount of memory available.
+  *
+  * %-EINVAL - Invalid number of segments specified
+  *
+  * %-EBUSY - Dirty or active segments are present in the range
+  */
+static int nilfs_sufile_truncate_range(struct inode *sufile,
+				       __u64 start, __u64 end)
+{
+	struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
+	struct buffer_head *header_bh;
+	struct buffer_head *su_bh;
+	struct nilfs_segment_usage *su, *su2;
+	size_t susz = NILFS_MDT(sufile)->mi_entry_size;
+	unsigned long segusages_per_block;
+	unsigned long nsegs, ncleaned;
+	__u64 segnum;
+	void *kaddr;
+	ssize_t n, nc;
+	int ret;
+	int j;
+
+	nsegs = nilfs_sufile_get_nsegments(sufile);
+
+	ret = -EINVAL;
+	if (start > end || start >= nsegs)
+		goto out;
+
+	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+	if (ret < 0)
+		goto out;
+
+	segusages_per_block = nilfs_sufile_segment_usages_per_block(sufile);
+	ncleaned = 0;
+
+	for (segnum = start; segnum <= end; segnum += n) {
+		n = min_t(unsigned long,
+			  segusages_per_block -
+				  nilfs_sufile_get_offset(sufile, segnum),
+			  end - segnum + 1);
+		ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0,
+							   &su_bh);
+		if (ret < 0) {
+			if (ret != -ENOENT)
+				goto out_header;
+			/* hole */
+			continue;
+		}
+		kaddr = kmap_atomic(su_bh->b_page);
+		su = nilfs_sufile_block_get_segment_usage(
+			sufile, segnum, su_bh, kaddr);
+		su2 = su;
+		for (j = 0; j < n; j++, su = (void *)su + susz) {
+			if ((le32_to_cpu(su->su_flags) &
+			     ~(1UL << NILFS_SEGMENT_USAGE_ERROR)) ||
+			    nilfs_segment_is_active(nilfs, segnum + j)) {
+				ret = -EBUSY;
+				kunmap_atomic(kaddr);
+				brelse(su_bh);
+				goto out_header;
+			}
+		}
+		nc = 0;
+		for (su = su2, j = 0; j < n; j++, su = (void *)su + susz) {
+			if (nilfs_segment_usage_error(su)) {
+				nilfs_segment_usage_set_clean(su);
+				nc++;
+			}
+		}
+		kunmap_atomic(kaddr);
+		if (nc > 0) {
+			mark_buffer_dirty(su_bh);
+			ncleaned += nc;
+		}
+		brelse(su_bh);
+
+		if (n == segusages_per_block) {
+			/* make hole */
+			nilfs_sufile_delete_segment_usage_block(sufile, segnum);
+		}
+	}
+	ret = 0;
+
+out_header:
+	if (ncleaned > 0) {
+		NILFS_SUI(sufile)->ncleansegs += ncleaned;
+		nilfs_sufile_mod_counter(header_bh, ncleaned, 0);
+		nilfs_mdt_mark_dirty(sufile);
+	}
+	brelse(header_bh);
+out:
+	return ret;
+}
+
+/**
+ * nilfs_sufile_resize - resize segment array
+ * @sufile: inode of segment usage file
+ * @newnsegs: new number of segments
+ *
+ * Return Value: On success, 0 is returned.  On error, one of the
+ * following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOSPC - Enough free space is not left for shrinking
+ *
+ * %-EBUSY - Dirty or active segments exist in the region to be truncated
+ */
+int nilfs_sufile_resize(struct inode *sufile, __u64 newnsegs)
+{
+	struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
+	struct buffer_head *header_bh;
+	struct nilfs_sufile_header *header;
+	struct nilfs_sufile_info *sui = NILFS_SUI(sufile);
+	void *kaddr;
+	unsigned long nsegs, nrsvsegs;
+	int ret = 0;
+
+	down_write(&NILFS_MDT(sufile)->mi_sem);
+
+	nsegs = nilfs_sufile_get_nsegments(sufile);
+	if (nsegs == newnsegs)
+		goto out;
+
+	ret = -ENOSPC;
+	nrsvsegs = nilfs_nrsvsegs(nilfs, newnsegs);
+	if (newnsegs < nsegs && nsegs - newnsegs + nrsvsegs > sui->ncleansegs)
+		goto out;
+
+	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+	if (ret < 0)
+		goto out;
+
+	if (newnsegs > nsegs) {
+		sui->ncleansegs += newnsegs - nsegs;
+	} else /* newnsegs < nsegs */ {
+		ret = nilfs_sufile_truncate_range(sufile, newnsegs, nsegs - 1);
+		if (ret < 0)
+			goto out_header;
+
+		sui->ncleansegs -= nsegs - newnsegs;
+	}
+
+	kaddr = kmap_atomic(header_bh->b_page);
+	header = kaddr + bh_offset(header_bh);
+	header->sh_ncleansegs = cpu_to_le64(sui->ncleansegs);
+	kunmap_atomic(kaddr);
+
+	mark_buffer_dirty(header_bh);
 	nilfs_mdt_mark_dirty(sufile);
+	nilfs_set_nsegments(nilfs, newnsegs);
+
+out_header:
+	brelse(header_bh);
+out:
+	up_write(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
 }
 
 /**
@@ -583,7 +818,7 @@ ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum, void *buf,
 	struct nilfs_segment_usage *su;
 	struct nilfs_suinfo *si = buf;
 	size_t susz = NILFS_MDT(sufile)->mi_entry_size;
-	struct the_nilfs *nilfs = NILFS_I_NILFS(sufile);
+	struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
 	void *kaddr;
 	unsigned long nsegs, segusages_per_block;
 	ssize_t n;
@@ -611,7 +846,7 @@ ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum, void *buf,
 			continue;
 		}
 
-		kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
+		kaddr = kmap_atomic(su_bh->b_page);
 		su = nilfs_sufile_block_get_segment_usage(
 			sufile, segnum, su_bh, kaddr);
 		for (j = 0; j < n;
@@ -624,7 +859,7 @@ ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum, void *buf,
 				si->sui_flags |=
 					(1UL << NILFS_SEGMENT_USAGE_ACTIVE);
 		}
-		kunmap_atomic(kaddr, KM_USER0);
+		kunmap_atomic(kaddr);
 		brelse(su_bh);
 	}
 	ret = nsegs;
@@ -635,6 +870,289 @@ ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum, void *buf,
 }
 
 /**
+ * nilfs_sufile_set_suinfo - sets segment usage info
+ * @sufile: inode of segment usage file
+ * @buf: array of suinfo_update
+ * @supsz: byte size of suinfo_update
+ * @nsup: size of suinfo_update array
+ *
+ * Description: Takes an array of nilfs_suinfo_update structs and updates
+ * segment usage accordingly. Only the fields indicated by the sup_flags
+ * are updated.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the
+ * following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-EINVAL - Invalid values in input (segment number, flags or nblocks)
+ */
+ssize_t nilfs_sufile_set_suinfo(struct inode *sufile, void *buf,
+				unsigned supsz, size_t nsup)
+{
+	struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
+	struct buffer_head *header_bh, *bh;
+	struct nilfs_suinfo_update *sup, *supend = buf + supsz * nsup;
+	struct nilfs_segment_usage *su;
+	void *kaddr;
+	unsigned long blkoff, prev_blkoff;
+	int cleansi, cleansu, dirtysi, dirtysu;
+	long ncleaned = 0, ndirtied = 0;
+	int ret = 0;
+
+	if (unlikely(nsup == 0))
+		return ret;
+
+	for (sup = buf; sup < supend; sup = (void *)sup + supsz) {
+		if (sup->sup_segnum >= nilfs->ns_nsegments
+			|| (sup->sup_flags &
+				(~0UL << __NR_NILFS_SUINFO_UPDATE_FIELDS))
+			|| (nilfs_suinfo_update_nblocks(sup) &&
+				sup->sup_sui.sui_nblocks >
+				nilfs->ns_blocks_per_segment))
+			return -EINVAL;
+	}
+
+	down_write(&NILFS_MDT(sufile)->mi_sem);
+
+	ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+	if (ret < 0)
+		goto out_sem;
+
+	sup = buf;
+	blkoff = nilfs_sufile_get_blkoff(sufile, sup->sup_segnum);
+	ret = nilfs_mdt_get_block(sufile, blkoff, 1, NULL, &bh);
+	if (ret < 0)
+		goto out_header;
+
+	for (;;) {
+		kaddr = kmap_atomic(bh->b_page);
+		su = nilfs_sufile_block_get_segment_usage(
+			sufile, sup->sup_segnum, bh, kaddr);
+
+		if (nilfs_suinfo_update_lastmod(sup))
+			su->su_lastmod = cpu_to_le64(sup->sup_sui.sui_lastmod);
+
+		if (nilfs_suinfo_update_nblocks(sup))
+			su->su_nblocks = cpu_to_le32(sup->sup_sui.sui_nblocks);
+
+		if (nilfs_suinfo_update_flags(sup)) {
+			/*
+			 * Active flag is a virtual flag projected by running
+			 * nilfs kernel code - drop it not to write it to
+			 * disk.
+			 */
+			sup->sup_sui.sui_flags &=
+					~(1UL << NILFS_SEGMENT_USAGE_ACTIVE);
+
+			cleansi = nilfs_suinfo_clean(&sup->sup_sui);
+			cleansu = nilfs_segment_usage_clean(su);
+			dirtysi = nilfs_suinfo_dirty(&sup->sup_sui);
+			dirtysu = nilfs_segment_usage_dirty(su);
+
+			if (cleansi && !cleansu)
+				++ncleaned;
+			else if (!cleansi && cleansu)
+				--ncleaned;
+
+			if (dirtysi && !dirtysu)
+				++ndirtied;
+			else if (!dirtysi && dirtysu)
+				--ndirtied;
+
+			su->su_flags = cpu_to_le32(sup->sup_sui.sui_flags);
+		}
+
+		kunmap_atomic(kaddr);
+
+		sup = (void *)sup + supsz;
+		if (sup >= supend)
+			break;
+
+		prev_blkoff = blkoff;
+		blkoff = nilfs_sufile_get_blkoff(sufile, sup->sup_segnum);
+		if (blkoff == prev_blkoff)
+			continue;
+
+		/* get different block */
+		mark_buffer_dirty(bh);
+		put_bh(bh);
+		ret = nilfs_mdt_get_block(sufile, blkoff, 1, NULL, &bh);
+		if (unlikely(ret < 0))
+			goto out_mark;
+	}
+	mark_buffer_dirty(bh);
+	put_bh(bh);
+
+ out_mark:
+	if (ncleaned || ndirtied) {
+		nilfs_sufile_mod_counter(header_bh, (u64)ncleaned,
+				(u64)ndirtied);
+		NILFS_SUI(sufile)->ncleansegs += ncleaned;
+	}
+	nilfs_mdt_mark_dirty(sufile);
+ out_header:
+	put_bh(header_bh);
+ out_sem:
+	up_write(&NILFS_MDT(sufile)->mi_sem);
+	return ret;
+}
+
+/**
+ * nilfs_sufile_trim_fs() - trim ioctl handle function
+ * @sufile: inode of segment usage file
+ * @range: fstrim_range structure
+ *
+ * start:	First Byte to trim
+ * len:		number of Bytes to trim from start
+ * minlen:	minimum extent length in Bytes
+ *
+ * Decription: nilfs_sufile_trim_fs goes through all segments containing bytes
+ * from start to start+len. start is rounded up to the next block boundary
+ * and start+len is rounded down. For each clean segment blkdev_issue_discard
+ * function is invoked.
+ *
+ * Return Value: On success, 0 is returned or negative error code, otherwise.
+ */
+int nilfs_sufile_trim_fs(struct inode *sufile, struct fstrim_range *range)
+{
+	struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
+	struct buffer_head *su_bh;
+	struct nilfs_segment_usage *su;
+	void *kaddr;
+	size_t n, i, susz = NILFS_MDT(sufile)->mi_entry_size;
+	sector_t seg_start, seg_end, start_block, end_block;
+	sector_t start = 0, nblocks = 0;
+	u64 segnum, segnum_end, minlen, len, max_blocks, ndiscarded = 0;
+	int ret = 0;
+	unsigned int sects_per_block;
+
+	sects_per_block = (1 << nilfs->ns_blocksize_bits) /
+			bdev_logical_block_size(nilfs->ns_bdev);
+	len = range->len >> nilfs->ns_blocksize_bits;
+	minlen = range->minlen >> nilfs->ns_blocksize_bits;
+	max_blocks = ((u64)nilfs->ns_nsegments * nilfs->ns_blocks_per_segment);
+
+	if (!len || range->start >= max_blocks << nilfs->ns_blocksize_bits)
+		return -EINVAL;
+
+	start_block = (range->start + nilfs->ns_blocksize - 1) >>
+			nilfs->ns_blocksize_bits;
+
+	/*
+	 * range->len can be very large (actually, it is set to
+	 * ULLONG_MAX by default) - truncate upper end of the range
+	 * carefully so as not to overflow.
+	 */
+	if (max_blocks - start_block < len)
+		end_block = max_blocks - 1;
+	else
+		end_block = start_block + len - 1;
+
+	segnum = nilfs_get_segnum_of_block(nilfs, start_block);
+	segnum_end = nilfs_get_segnum_of_block(nilfs, end_block);
+
+	down_read(&NILFS_MDT(sufile)->mi_sem);
+
+	while (segnum <= segnum_end) {
+		n = nilfs_sufile_segment_usages_in_block(sufile, segnum,
+				segnum_end);
+
+		ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0,
+							   &su_bh);
+		if (ret < 0) {
+			if (ret != -ENOENT)
+				goto out_sem;
+			/* hole */
+			segnum += n;
+			continue;
+		}
+
+		kaddr = kmap_atomic(su_bh->b_page);
+		su = nilfs_sufile_block_get_segment_usage(sufile, segnum,
+				su_bh, kaddr);
+		for (i = 0; i < n; ++i, ++segnum, su = (void *)su + susz) {
+			if (!nilfs_segment_usage_clean(su))
+				continue;
+
+			nilfs_get_segment_range(nilfs, segnum, &seg_start,
+						&seg_end);
+
+			if (!nblocks) {
+				/* start new extent */
+				start = seg_start;
+				nblocks = seg_end - seg_start + 1;
+				continue;
+			}
+
+			if (start + nblocks == seg_start) {
+				/* add to previous extent */
+				nblocks += seg_end - seg_start + 1;
+				continue;
+			}
+
+			/* discard previous extent */
+			if (start < start_block) {
+				nblocks -= start_block - start;
+				start = start_block;
+			}
+
+			if (nblocks >= minlen) {
+				kunmap_atomic(kaddr);
+
+				ret = blkdev_issue_discard(nilfs->ns_bdev,
+						start * sects_per_block,
+						nblocks * sects_per_block,
+						GFP_NOFS, 0);
+				if (ret < 0) {
+					put_bh(su_bh);
+					goto out_sem;
+				}
+
+				ndiscarded += nblocks;
+				kaddr = kmap_atomic(su_bh->b_page);
+				su = nilfs_sufile_block_get_segment_usage(
+					sufile, segnum, su_bh, kaddr);
+			}
+
+			/* start new extent */
+			start = seg_start;
+			nblocks = seg_end - seg_start + 1;
+		}
+		kunmap_atomic(kaddr);
+		put_bh(su_bh);
+	}
+
+
+	if (nblocks) {
+		/* discard last extent */
+		if (start < start_block) {
+			nblocks -= start_block - start;
+			start = start_block;
+		}
+		if (start + nblocks > end_block + 1)
+			nblocks = end_block - start + 1;
+
+		if (nblocks >= minlen) {
+			ret = blkdev_issue_discard(nilfs->ns_bdev,
+					start * sects_per_block,
+					nblocks * sects_per_block,
+					GFP_NOFS, 0);
+			if (!ret)
+				ndiscarded += nblocks;
+		}
+	}
+
+out_sem:
+	up_read(&NILFS_MDT(sufile)->mi_sem);
+
+	range->len = ndiscarded << nilfs->ns_blocksize_bits;
+	return ret;
+}
+
+/**
  * nilfs_sufile_read - read or get sufile inode
  * @sb: super block instance
  * @susize: size of a segment usage entry
@@ -651,6 +1169,18 @@ int nilfs_sufile_read(struct super_block *sb, size_t susize,
 	void *kaddr;
 	int err;
 
+	if (susize > sb->s_blocksize) {
+		printk(KERN_ERR
+		       "NILFS: too large segment usage size: %zu bytes.\n",
+		       susize);
+		return -EINVAL;
+	} else if (susize < NILFS_MIN_SEGMENT_USAGE_SIZE) {
+		printk(KERN_ERR
+		       "NILFS: too small segment usage size: %zu bytes.\n",
+		       susize);
+		return -EINVAL;
+	}
+
 	sufile = nilfs_iget_locked(sb, NULL, NILFS_SUFILE_INO);
 	if (unlikely(!sufile))
 		return -ENOMEM;
@@ -673,12 +1203,15 @@ int nilfs_sufile_read(struct super_block *sb, size_t susize,
 		goto failed;
 
 	sui = NILFS_SUI(sufile);
-	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
+	kaddr = kmap_atomic(header_bh->b_page);
 	header = kaddr + bh_offset(header_bh);
 	sui->ncleansegs = le64_to_cpu(header->sh_ncleansegs);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 	brelse(header_bh);
 
+	sui->allocmax = nilfs_sufile_get_nsegments(sufile) - 1;
+	sui->allocmin = 0;
+
 	unlock_new_inode(sufile);
  out:
 	*inodep = sufile;