nilfs2: add sufile function that can modify multiple segment usages

This is a preparation for the later cleanup patch ("nilfs2: remove
list of freeing segments").

This adds nilfs_sufile_updatev() to sufile, which can modify multiple
segment usages at a time.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 97 insertions, 0 deletions

diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
index 98e68677f045..da127325fdaa 100644
--- a/fs/nilfs2/sufile.c
+++ b/fs/nilfs2/sufile.c
@@ -18,6 +18,7 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  *
  * Written by Koji Sato <koji@osrg.net>.
+ * Rivised by Ryusuke Konishi <ryusuke@osrg.net>.
  */
 
 #include <linux/kernel.h>
@@ -108,6 +109,102 @@ static void nilfs_sufile_mod_counter(struct buffer_head *header_bh,
         nilfs_mdt_mark_buffer_dirty(header_bh);
 }
 
+/**
+ * nilfs_sufile_updatev - modify multiple segment usages at a time
+ * @sufile: inode of segment usage file
+ * @segnumv: array of segment numbers
+ * @nsegs: size of @segnumv array
+ * @create: creation flag
+ * @ndone: place to store number of modified segments on @segnumv
+ * @dofunc: primitive operation for the update
+ *
+ * Description: nilfs_sufile_updatev() repeatedly calls @dofunc
+ * against the given array of segments.  The @dofunc is called with
+ * buffers of a header block and the sufile block in which the target
+ * segment usage entry is contained.  If @ndone is given, the number
+ * of successfully modified segments from the head is stored in the
+ * place @ndone points to.
+ *
+ * Return Value: On success, zero is returned.  On error, one of the
+ * following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - Given segment usage is in hole block (may be returned if
+ *            @create is zero)
+ *
+ * %-EINVAL - Invalid segment usage number
+ */
+int nilfs_sufile_updatev(struct inode *sufile, __u64 *segnumv, size_t nsegs,
+                         int create, size_t *ndone,
+                         void (*dofunc)(struct inode *, __u64,
+                                        struct buffer_head *,
+                                        struct buffer_head *))
+{
+        struct buffer_head *header_bh, *bh;
+        unsigned long blkoff, prev_blkoff;
+        __u64 *seg;
+        size_t nerr = 0, n = 0;
+        int ret = 0;
+
+        if (unlikely(nsegs == 0))
+                goto out;
+
+        down_write(&NILFS_MDT(sufile)->mi_sem);
+        for (seg = segnumv; seg < segnumv + nsegs; seg++) {
+                if (unlikely(*seg >= nilfs_sufile_get_nsegments(sufile))) {
+                        printk(KERN_WARNING
+                               "%s: invalid segment number: %llu\n", __func__,
+                               (unsigned long long)*seg);
+                        nerr++;
+                }
+        }
+        if (nerr > 0) {
+                ret = -EINVAL;
+                goto out_sem;
+        }
+
+        ret = nilfs_sufile_get_header_block(sufile, &header_bh);
+        if (ret < 0)
+                goto out_sem;
+
+        seg = segnumv;
+        blkoff = nilfs_sufile_get_blkoff(sufile, *seg);
+        ret = nilfs_mdt_get_block(sufile, blkoff, create, NULL, &bh);
+        if (ret < 0)
+                goto out_header;
+
+        for (;;) {
+                dofunc(sufile, *seg, header_bh, bh);
+
+                if (++seg >= segnumv + nsegs)
+                        break;
+                prev_blkoff = blkoff;
+                blkoff = nilfs_sufile_get_blkoff(sufile, *seg);
+                if (blkoff == prev_blkoff)
+                        continue;
+
+                /* get different block */
+                brelse(bh);
+                ret = nilfs_mdt_get_block(sufile, blkoff, create, NULL, &bh);
+                if (unlikely(ret < 0))
+                        goto out_header;
+        }
+        brelse(bh);
+
+ out_header:
+        n = seg - segnumv;
+        brelse(header_bh);
+ out_sem:
+        up_write(&NILFS_MDT(sufile)->mi_sem);
+ out:
+        if (ndone)
+                *ndone = n;
+        return ret;
+}
+
 int nilfs_sufile_update(struct inode *sufile, __u64 segnum, int create,
                         void (*dofunc)(struct inode *, __u64,
                                        struct buffer_head *,