nilfs2: segment buffer
This adds the segment buffer which is used to constuct logs.
[akpm@linux-foundation.org: BIO_RW_SYNC got removed]
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
new file mode 100644
index 0000000..3d3ea83
--- /dev/null
+++ b/fs/nilfs2/segbuf.c
@@ -0,0 +1,461 @@
+/*
+ * segbuf.c - NILFS segment buffer
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/crc32.h>
+#include "page.h"
+#include "segbuf.h"
+#include "seglist.h"
+
+
+static struct kmem_cache *nilfs_segbuf_cachep;
+
+static void nilfs_segbuf_init_once(void *obj)
+{
+ memset(obj, 0, sizeof(struct nilfs_segment_buffer));
+}
+
+int __init nilfs_init_segbuf_cache(void)
+{
+ nilfs_segbuf_cachep =
+ kmem_cache_create("nilfs2_segbuf_cache",
+ sizeof(struct nilfs_segment_buffer),
+ 0, SLAB_RECLAIM_ACCOUNT,
+ nilfs_segbuf_init_once);
+
+ return (nilfs_segbuf_cachep == NULL) ? -ENOMEM : 0;
+}
+
+void nilfs_destroy_segbuf_cache(void)
+{
+ kmem_cache_destroy(nilfs_segbuf_cachep);
+}
+
+struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
+{
+ struct nilfs_segment_buffer *segbuf;
+
+ segbuf = kmem_cache_alloc(nilfs_segbuf_cachep, GFP_NOFS);
+ if (unlikely(!segbuf))
+ return NULL;
+
+ segbuf->sb_super = sb;
+ INIT_LIST_HEAD(&segbuf->sb_list);
+ INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
+ INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
+ segbuf->sb_segent = NULL;
+ return segbuf;
+}
+
+void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
+{
+ struct nilfs_segment_entry *ent = segbuf->sb_segent;
+
+ if (ent != NULL && list_empty(&ent->list)) {
+ /* free isolated segment list head */
+ nilfs_free_segment_entry(segbuf->sb_segent);
+ segbuf->sb_segent = NULL;
+ }
+ kmem_cache_free(nilfs_segbuf_cachep, segbuf);
+}
+
+int nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
+ unsigned long offset, struct the_nilfs *nilfs)
+{
+ struct nilfs_segment_entry *ent;
+
+ segbuf->sb_segnum = segnum;
+ nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
+ &segbuf->sb_fseg_end);
+
+ segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
+ segbuf->sb_rest_blocks =
+ segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
+
+ /* Attach a segment list head */
+ ent = segbuf->sb_segent;
+ if (ent == NULL) {
+ segbuf->sb_segent = nilfs_alloc_segment_entry(segnum);
+ if (unlikely(!segbuf->sb_segent))
+ return -ENOMEM;
+ } else {
+ BUG_ON(ent->bh_su || !list_empty(&ent->list));
+ ent->segnum = segnum;
+ }
+ return 0;
+}
+
+void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
+ __u64 nextnum, struct the_nilfs *nilfs)
+{
+ segbuf->sb_nextnum = nextnum;
+ segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
+}
+
+int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
+{
+ struct buffer_head *bh;
+
+ bh = sb_getblk(segbuf->sb_super,
+ segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
+ if (unlikely(!bh))
+ return -ENOMEM;
+
+ nilfs_segbuf_add_segsum_buffer(segbuf, bh);
+ return 0;
+}
+
+int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
+ struct buffer_head **bhp)
+{
+ struct buffer_head *bh;
+
+ bh = sb_getblk(segbuf->sb_super,
+ segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
+ if (unlikely(!bh))
+ return -ENOMEM;
+
+ nilfs_segbuf_add_payload_buffer(segbuf, bh);
+ *bhp = bh;
+ return 0;
+}
+
+int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
+ time_t ctime)
+{
+ int err;
+
+ segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
+ err = nilfs_segbuf_extend_segsum(segbuf);
+ if (unlikely(err))
+ return err;
+
+ segbuf->sb_sum.flags = flags;
+ segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
+ segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
+ segbuf->sb_sum.ctime = ctime;
+
+ segbuf->sb_io_error = 0;
+ return 0;
+}
+
+/*
+ * Setup segument summary
+ */
+void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
+{
+ struct nilfs_segment_summary *raw_sum;
+ struct buffer_head *bh_sum;
+
+ bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
+ struct buffer_head, b_assoc_buffers);
+ raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;
+
+ raw_sum->ss_magic = cpu_to_le32(NILFS_SEGSUM_MAGIC);
+ raw_sum->ss_bytes = cpu_to_le16(sizeof(*raw_sum));
+ raw_sum->ss_flags = cpu_to_le16(segbuf->sb_sum.flags);
+ raw_sum->ss_seq = cpu_to_le64(segbuf->sb_sum.seg_seq);
+ raw_sum->ss_create = cpu_to_le64(segbuf->sb_sum.ctime);
+ raw_sum->ss_next = cpu_to_le64(segbuf->sb_sum.next);
+ raw_sum->ss_nblocks = cpu_to_le32(segbuf->sb_sum.nblocks);
+ raw_sum->ss_nfinfo = cpu_to_le32(segbuf->sb_sum.nfinfo);
+ raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
+ raw_sum->ss_pad = 0;
+}
+
+/*
+ * CRC calculation routines
+ */
+void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
+ u32 seed)
+{
+ struct buffer_head *bh;
+ struct nilfs_segment_summary *raw_sum;
+ unsigned long size, bytes = segbuf->sb_sum.sumbytes;
+ u32 crc;
+
+ bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
+ b_assoc_buffers);
+
+ raw_sum = (struct nilfs_segment_summary *)bh->b_data;
+ size = min_t(unsigned long, bytes, bh->b_size);
+ crc = crc32_le(seed,
+ (unsigned char *)raw_sum +
+ sizeof(raw_sum->ss_datasum) + sizeof(raw_sum->ss_sumsum),
+ size - (sizeof(raw_sum->ss_datasum) +
+ sizeof(raw_sum->ss_sumsum)));
+
+ list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
+ b_assoc_buffers) {
+ bytes -= size;
+ size = min_t(unsigned long, bytes, bh->b_size);
+ crc = crc32_le(crc, bh->b_data, size);
+ }
+ raw_sum->ss_sumsum = cpu_to_le32(crc);
+}
+
+void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
+ u32 seed)
+{
+ struct buffer_head *bh;
+ struct nilfs_segment_summary *raw_sum;
+ void *kaddr;
+ u32 crc;
+
+ bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
+ b_assoc_buffers);
+ raw_sum = (struct nilfs_segment_summary *)bh->b_data;
+ crc = crc32_le(seed,
+ (unsigned char *)raw_sum + sizeof(raw_sum->ss_datasum),
+ bh->b_size - sizeof(raw_sum->ss_datasum));
+
+ list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
+ b_assoc_buffers) {
+ crc = crc32_le(crc, bh->b_data, bh->b_size);
+ }
+ list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
+ kaddr = kmap_atomic(bh->b_page, KM_USER0);
+ crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
+ kunmap_atomic(kaddr, KM_USER0);
+ }
+ raw_sum->ss_datasum = cpu_to_le32(crc);
+}
+
+void nilfs_release_buffers(struct list_head *list)
+{
+ struct buffer_head *bh, *n;
+
+ list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
+ list_del_init(&bh->b_assoc_buffers);
+ if (buffer_nilfs_allocated(bh)) {
+ struct page *clone_page = bh->b_page;
+
+ /* remove clone page */
+ brelse(bh);
+ page_cache_release(clone_page); /* for each bh */
+ if (page_count(clone_page) <= 2) {
+ lock_page(clone_page);
+ nilfs_free_private_page(clone_page);
+ }
+ continue;
+ }
+ brelse(bh);
+ }
+}
+
+/*
+ * BIO operations
+ */
+static void nilfs_end_bio_write(struct bio *bio, int err)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct nilfs_write_info *wi = bio->bi_private;
+
+ if (err == -EOPNOTSUPP) {
+ set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+ bio_put(bio);
+ /* to be detected by submit_seg_bio() */
+ }
+
+ if (!uptodate)
+ atomic_inc(&wi->err);
+
+ bio_put(bio);
+ complete(&wi->bio_event);
+}
+
+static int nilfs_submit_seg_bio(struct nilfs_write_info *wi, int mode)
+{
+ struct bio *bio = wi->bio;
+ int err;
+
+ if (wi->nbio > 0 && bdi_write_congested(wi->bdi)) {
+ wait_for_completion(&wi->bio_event);
+ wi->nbio--;
+ if (unlikely(atomic_read(&wi->err))) {
+ bio_put(bio);
+ err = -EIO;
+ goto failed;
+ }
+ }
+
+ bio->bi_end_io = nilfs_end_bio_write;
+ bio->bi_private = wi;
+ bio_get(bio);
+ submit_bio(mode, bio);
+ if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
+ bio_put(bio);
+ err = -EOPNOTSUPP;
+ goto failed;
+ }
+ wi->nbio++;
+ bio_put(bio);
+
+ wi->bio = NULL;
+ wi->rest_blocks -= wi->end - wi->start;
+ wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
+ wi->start = wi->end;
+ return 0;
+
+ failed:
+ wi->bio = NULL;
+ return err;
+}
+
+/**
+ * nilfs_alloc_seg_bio - allocate a bio for writing segment.
+ * @sb: super block
+ * @start: beginning disk block number of this BIO.
+ * @nr_vecs: request size of page vector.
+ *
+ * alloc_seg_bio() allocates a new BIO structure and initialize it.
+ *
+ * Return Value: On success, pointer to the struct bio is returned.
+ * On error, NULL is returned.
+ */
+static struct bio *nilfs_alloc_seg_bio(struct super_block *sb, sector_t start,
+ int nr_vecs)
+{
+ struct bio *bio;
+
+ bio = bio_alloc(GFP_NOWAIT, nr_vecs);
+ if (bio == NULL) {
+ while (!bio && (nr_vecs >>= 1))
+ bio = bio_alloc(GFP_NOWAIT, nr_vecs);
+ }
+ if (likely(bio)) {
+ bio->bi_bdev = sb->s_bdev;
+ bio->bi_sector = (sector_t)start << (sb->s_blocksize_bits - 9);
+ }
+ return bio;
+}
+
+void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
+ struct nilfs_write_info *wi)
+{
+ wi->bio = NULL;
+ wi->rest_blocks = segbuf->sb_sum.nblocks;
+ wi->max_pages = bio_get_nr_vecs(wi->sb->s_bdev);
+ wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
+ wi->start = wi->end = 0;
+ wi->nbio = 0;
+ wi->blocknr = segbuf->sb_pseg_start;
+
+ atomic_set(&wi->err, 0);
+ init_completion(&wi->bio_event);
+}
+
+static int nilfs_submit_bh(struct nilfs_write_info *wi, struct buffer_head *bh,
+ int mode)
+{
+ int len, err;
+
+ BUG_ON(wi->nr_vecs <= 0);
+ repeat:
+ if (!wi->bio) {
+ wi->bio = nilfs_alloc_seg_bio(wi->sb, wi->blocknr + wi->end,
+ wi->nr_vecs);
+ if (unlikely(!wi->bio))
+ return -ENOMEM;
+ }
+
+ len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
+ if (len == bh->b_size) {
+ wi->end++;
+ return 0;
+ }
+ /* bio is FULL */
+ err = nilfs_submit_seg_bio(wi, mode);
+ /* never submit current bh */
+ if (likely(!err))
+ goto repeat;
+ return err;
+}
+
+int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
+ struct nilfs_write_info *wi)
+{
+ struct buffer_head *bh;
+ int res, rw = WRITE;
+
+ list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
+ res = nilfs_submit_bh(wi, bh, rw);
+ if (unlikely(res))
+ goto failed_bio;
+ }
+
+ list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
+ res = nilfs_submit_bh(wi, bh, rw);
+ if (unlikely(res))
+ goto failed_bio;
+ }
+
+ if (wi->bio) {
+ /*
+ * Last BIO is always sent through the following
+ * submission.
+ */
+ rw |= (1 << BIO_RW_SYNCIO);
+ res = nilfs_submit_seg_bio(wi, rw);
+ if (unlikely(res))
+ goto failed_bio;
+ }
+
+ res = 0;
+ out:
+ return res;
+
+ failed_bio:
+ atomic_inc(&wi->err);
+ goto out;
+}
+
+/**
+ * nilfs_segbuf_wait - wait for completion of requested BIOs
+ * @wi: nilfs_write_info
+ *
+ * Return Value: On Success, 0 is returned. On Error, one of the following
+ * negative error code is returned.
+ *
+ * %-EIO - I/O error
+ */
+int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf,
+ struct nilfs_write_info *wi)
+{
+ int err = 0;
+
+ if (!wi->nbio)
+ return 0;
+
+ do {
+ wait_for_completion(&wi->bio_event);
+ } while (--wi->nbio > 0);
+
+ if (unlikely(atomic_read(&wi->err) > 0)) {
+ printk(KERN_ERR "NILFS: IO error writing segment\n");
+ err = -EIO;
+ segbuf->sb_io_error = 1;
+ }
+ return err;
+}