[PATCH 14/17] [LogFS] super.c

Joern Engel
2009-11-20T20:22:54Z

---
fs/logfs/super.c | 634 ++++++++++

diff --git a/fs/logfs/super.c b/fs/logfs/super.c
new file mode 100644
index 0000000..d128a2c
--- /dev/null
+++ b/fs/logfs/super.c
@@ -0,0 +1,634 @@
+/*
+ * fs/logfs/super.c
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
+ *
+ * Generally contains mount/umount code and also serves as a dump area for
+ * any functions that don't fit elsewhere and neither justify a file of their
+ * own.
+ */
+#include "logfs.h"
+#include <linux/bio.h>
+#include <linux/mtd/mtd.h>
+#include <linux/statfs.h>
+#include <linux/buffer_head.h>
+
+static DEFINE_MUTEX(emergency_mutex);
+static struct page *emergency_page;
+
+struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index)
+{
+ filler_t *filler = (filler_t *)mapping->a_ops->readpage;
+ struct page *page;
+ int err;
+
+ page = read_cache_page(mapping, index, filler, NULL);
+ if (page)
+ return page;
+
+ /* No more pages available, switch to emergency page */
+ printk(KERN_INFO"Logfs: Using emergency page\n");
+ mutex_lock(&emergency_mutex);
+ err = filler(NULL, emergency_page);
+ if (err) {
+ mutex_unlock(&emergency_mutex);
+ printk(KERN_EMERG"Logfs: Error reading emergency page\n");
+ return ERR_PTR(err);
+ }
+ return emergency_page;
+}
+
+void emergency_read_end(struct page *page)
+{
+ if (page == emergency_page)
+ mutex_unlock(&emergency_mutex);
+ else
+ page_cache_release(page);
+}
+
+static void dump_segfile(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_segment_entry se;
+ u32 segno;
+
+ for (segno = 0; segno < super->s_no_segs; segno++) {
+ logfs_get_segment_entry(sb, segno, &se);
+ printk("%3x: %6x %8x", segno, be32_to_cpu(se.ec_level),
+ be32_to_cpu(se.valid));
+ if (++segno < super->s_no_segs) {
+ logfs_get_segment_entry(sb, segno, &se);
+ printk(" %6x %8x", be32_to_cpu(se.ec_level),
+ be32_to_cpu(se.valid));
+ }
+ if (++segno < super->s_no_segs) {
+ logfs_get_segment_entry(sb, segno, &se);
+ printk(" %6x %8x", be32_to_cpu(se.ec_level),
+ be32_to_cpu(se.valid));
+ }
+ if (++segno < super->s_no_segs) {
+ logfs_get_segment_entry(sb, segno, &se);
+ printk(" %6x %8x", be32_to_cpu(se.ec_level),
+ be32_to_cpu(se.valid));
+ }
+ printk("\n");
+ }
+}
+
+/*
+ * logfs_crash_dump - dump debug information to device
+ *
+ * The LogFS superblock only occupies part of a segment. This function will
+ * write as much debug information as it can gather into the spare space.
+ */
+void logfs_crash_dump(struct super_block *sb)
+{
+ dump_segfile(sb);
+}
+
+/*
+ * TODO: move to lib/string.c
+ */
+/**
+ * memchr_inv - Find a character in an area of memory.
+ * @s: The memory area
+ * @c: The byte to search for
+ * @n: The size of the area.
+ *
+ * returns the address of the first character other than @c, or %NULL
+ * if the whole buffer contains just @c.
+ */
+void *memchr_inv(const void *s, int c, size_t n)
+{
+ const unsigned char *p = s;
+ while (n-- != 0)
+ if ((unsigned char)c != *p++)
+ return (void *)(p - 1);
+
+ return NULL;
+}
+
+/*
+ * FIXME: There should be a reserve for root, similar to ext2.
+ */
+int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
+{
+ struct super_block *sb = dentry->d_sb;
+ struct logfs_super *super = logfs_super(sb);
+
+ stats->f_type = LOGFS_MAGIC_U32;
+ stats->f_bsize = sb->s_blocksize;
+ stats->f_blocks = super->s_size >> LOGFS_BLOCK_BITS >> 3;
+ stats->f_bfree = super->s_free_bytes >> sb->s_blocksize_bits;
+ stats->f_bavail = super->s_free_bytes >> sb->s_blocksize_bits;
+ stats->f_files = 0;
+ stats->f_ffree = 0;
+ stats->f_namelen = LOGFS_MAX_NAMELEN;
+ return 0;
+}
+
+static int logfs_sb_set(struct super_block *sb, void *_super)
+{
+ struct logfs_super *super = _super;
+
+ sb->s_fs_info = super;
+ sb->s_mtd = super->s_mtd;
+ sb->s_bdev = super->s_bdev;
+ return 0;
+}
+
+static int logfs_sb_test(struct super_block *sb, void *_super)
+{
+ struct logfs_super *super = _super;
+ struct mtd_info *mtd = super->s_mtd;
+
+ if (mtd && sb->s_mtd == mtd)
+ return 1;
+ if (super->s_bdev && sb->s_bdev == super->s_bdev)
+ return 1;
+ return 0;
+}
+
+static void set_segment_header(struct logfs_segment_header *sh, u8 type,
+ u8 level, u32 segno, u32 ec)
+{
+ sh->pad = 0;
+ sh->type = type;
+ sh->level = level;
+ sh->segno = cpu_to_be32(segno);
+ sh->ec = cpu_to_be32(ec);
+ sh->gec = cpu_to_be64(segno);
+ sh->crc = logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4);
+}
+
+static void logfs_write_ds(struct super_block *sb, struct logfs_disk_super *ds,
+ u32 segno, u32 ec)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_segment_header *sh = &ds->ds_sh;
+ int i;
+
+ memset(ds, 0, sizeof(*ds));
+ set_segment_header(sh, SEG_SUPER, 0, segno, ec);
+
+ ds->ds_ifile_levels = super->s_ifile_levels;
+ ds->ds_iblock_levels = super->s_iblock_levels;
+ ds->ds_data_levels = super->s_data_levels; /* XXX: Remove */
+ ds->ds_segment_shift = super->s_segshift;
+ ds->ds_block_shift = sb->s_blocksize_bits;
+ ds->ds_write_shift = super->s_writeshift;
+ ds->ds_filesystem_size = cpu_to_be64(super->s_size);
+ ds->ds_segment_size = cpu_to_be32(super->s_segsize);
+ ds->ds_bad_seg_reserve = cpu_to_be32(super->s_bad_seg_reserve);
+ ds->ds_feature_incompat = cpu_to_be64(super->s_feature_incompat);
+ ds->ds_feature_ro_compat= cpu_to_be64(super->s_feature_ro_compat);
+ ds->ds_feature_compat = cpu_to_be64(super->s_feature_compat);
+ ds->ds_feature_flags = cpu_to_be64(super->s_feature_flags);
+ ds->ds_root_reserve = cpu_to_be64(super->s_root_reserve);
+ ds->ds_speed_reserve = cpu_to_be64(super->s_speed_reserve);
+ journal_for_each(i)
+ ds->ds_journal_seg[i] = cpu_to_be32(super->s_journal_seg[i]);
+ ds->ds_magic = cpu_to_be64(LOGFS_MAGIC);
+ ds->ds_crc = logfs_crc32(ds, sizeof(*ds),
+ LOGFS_SEGMENT_HEADERSIZE + 12);
+}
+
+static int write_one_sb(struct super_block *sb,
+ struct page *(*find_sb)(struct super_block *sb, u64 *ofs))
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_disk_super *ds;
+ struct logfs_segment_entry se;
+ struct page *page;
+ u64 ofs;
+ u32 ec, segno;
+ int err;
+
+ page = find_sb(sb, &ofs);
+ if (!page)
+ return -EIO;
+ ds = page_address(page);
+ segno = seg_no(sb, ofs);
+ logfs_get_segment_entry(sb, segno, &se);
+ ec = be32_to_cpu(se.ec_level) >> 4;
+ ec++;
+ logfs_set_segment_erased(sb, segno, ec, 0);
+ logfs_write_ds(sb, ds, segno, ec);
+ err = super->s_devops->write_sb(sb, page);
+ page_cache_release(page);
+ return err;
+}
+
+int logfs_write_sb(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ int err;
+
+ /* First superblock */
+ err = write_one_sb(sb, super->s_devops->find_first_sb);
+ if (err)
+ return err;
+
+ /* Last superblock */
+ err = write_one_sb(sb, super->s_devops->find_last_sb);
+ if (err)
+ return err;
+ return 0;
+}
+
+static int ds_cmp(const void *ds0, const void *ds1)
+{
+ size_t len = sizeof(struct logfs_disk_super);
+
+ /* We know the segment headers differ, so ignore them */
+ len -= LOGFS_SEGMENT_HEADERSIZE;
+ ds0 += LOGFS_SEGMENT_HEADERSIZE;
+ ds1 += LOGFS_SEGMENT_HEADERSIZE;
+ return memcmp(ds0, ds1, len);
+}
+
+static int logfs_recover_sb(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_disk_super _ds0, *ds0 = &_ds0;
+ struct logfs_disk_super _ds1, *ds1 = &_ds1;
+ int err, valid0, valid1;
+
+ /* read first superblock */
+ err = wbuf_read(sb, super->s_sb_ofs[0], sizeof(*ds0), ds0);
+ if (err)
+ return err;
+ /* read last superblock */
+ err = wbuf_read(sb, super->s_sb_ofs[1], sizeof(*ds1), ds1);
+ if (err)
+ return err;
+ valid0 = logfs_check_ds(ds0) == 0;
+ valid1 = logfs_check_ds(ds1) == 0;
+
+ if (!valid0 && valid1) {
+ printk(KERN_INFO"First superblock is invalid - fixing.\n");
+ return write_one_sb(sb, super->s_devops->find_first_sb);
+ }
+ if (valid0 && !valid1) {
+ printk(KERN_INFO"Last superblock is invalid - fixing.\n");
+ return write_one_sb(sb, super->s_devops->find_last_sb);
+ }
+ if (valid0 && valid1 && ds_cmp(ds0, ds1)) {
+ printk(KERN_INFO"Superblocks don't match - fixing.\n");
+ return write_one_sb(sb, super->s_devops->find_last_sb);
+ }
+ /* If neither is valid now, something's wrong. Didn't we properly
+ * check them before?!? */
+ BUG_ON(!valid0 && !valid1);
+ return 0;
+}
+
+static int logfs_make_writeable(struct super_block *sb)
+{
+ int err;
+
+ /* Repair any broken superblock copies */
+ err = logfs_recover_sb(sb);
+ if (err)
+ return err;
+
+ /* Check areas for trailing unaccounted data */
+ err = logfs_check_areas(sb);
+ if (err)
+ return err;
+
+ err = logfs_open_segfile(sb);
+ if (err)
+ return err;
+
+ /* Do one GC pass before any data gets dirtied */
+ logfs_gc_pass(sb);
+
+ /* after all initializations are done, replay the journal
+ * for rw-mounts, if necessary */
+ err = logfs_replay_journal(sb);
+ if (err)
+ return err;
+
+ return 0;
+}
+
+static int logfs_get_sb_final(struct super_block *sb, struct vfsmount *mnt)
+{
+ struct inode *rootdir;
+ int err;
+
+ /* root dir */
+ rootdir = logfs_iget(sb, LOGFS_INO_ROOT);
+ if (IS_ERR(rootdir))
+ goto fail;
+
+ sb->s_root = d_alloc_root(rootdir);
+ if (!sb->s_root)
+ goto fail;
+
+ /* FIXME: check for read-only mounts */
+ err = logfs_make_writeable(sb);
+ if (err)
+ goto fail2;
+
+ log_super("LogFS: Finished mounting\n");
+ simple_set_mnt(mnt, sb);
+ return 0;
+
+fail2:
+ iput(rootdir);
+fail:
+ iput(logfs_super(sb)->s_master_inode);
+ return -EIO;
+}
+
+int logfs_check_ds(struct logfs_disk_super *ds)
+{
+ struct logfs_segment_header *sh = &ds->ds_sh;
+
+ if (ds->ds_magic != cpu_to_be64(LOGFS_MAGIC))
+ return -EINVAL;
+ if (sh->crc != logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4))
+ return -EINVAL;
+ if (ds->ds_crc != logfs_crc32(ds, sizeof(*ds),
+ LOGFS_SEGMENT_HEADERSIZE + 12))
+ return -EINVAL;
+ return 0;
+}
+
+static struct page *find_super_block(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct page *first, *last;
+
+ first = super->s_devops->find_first_sb(sb, &super->s_sb_ofs[0]);
+ if (!first || IS_ERR(first))
+ return NULL;
+ last = super->s_devops->find_last_sb(sb, &super->s_sb_ofs[1]);
+ if (!last || IS_ERR(first)) {
+ page_cache_release(first);
+ return NULL;
+ }
+
+ if (!logfs_check_ds(page_address(first))) {
+ page_cache_release(last);
+ return first;
+ }
+
+ /* First one didn't work, try the second superblock */
+ if (!logfs_check_ds(page_address(last))) {
+ page_cache_release(first);
+ return last;
+ }
+
+ /* Neither worked, sorry folks */
+ page_cache_release(first);
+ page_cache_release(last);
+ return NULL;
+}
+
+static int __logfs_read_sb(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct page *page;
+ struct logfs_disk_super *ds;
+ int i;
+
+ page = find_super_block(sb);
+ if (!page)
+ return -EIO;
+
+ ds = page_address(page);
+ super->s_size = be64_to_cpu(ds->ds_filesystem_size);
+ super->s_root_reserve = be64_to_cpu(ds->ds_root_reserve);
+ super->s_speed_reserve = be64_to_cpu(ds->ds_speed_reserve);
+ super->s_bad_seg_reserve = be32_to_cpu(ds->ds_bad_seg_reserve);
+ super->s_segsize = 1 << ds->ds_segment_shift;
+ super->s_segmask = (1 << ds->ds_segment_shift) - 1;
+ super->s_segshift = ds->ds_segment_shift;
+ sb->s_blocksize = 1 << ds->ds_block_shift;
+ sb->s_blocksize_bits = ds->ds_block_shift;
+ super->s_writesize = 1 << ds->ds_write_shift;
+ super->s_writeshift = ds->ds_write_shift;
+ super->s_no_segs = super->s_size >> super->s_segshift;
+ super->s_no_blocks = super->s_segsize >> sb->s_blocksize_bits;
+ super->s_feature_incompat = be64_to_cpu(ds->ds_feature_incompat);
+ super->s_feature_ro_compat = be64_to_cpu(ds->ds_feature_ro_compat);
+ super->s_feature_compat = be64_to_cpu(ds->ds_feature_compat);
+ super->s_feature_flags = be64_to_cpu(ds->ds_feature_flags);
+
+ journal_for_each(i)
+ super->s_journal_seg[i] = be32_to_cpu(ds->ds_journal_seg[i]);
+
+ super->s_ifile_levels = ds->ds_ifile_levels;
+ super->s_iblock_levels = ds->ds_iblock_levels;
+ super->s_data_levels = ds->ds_data_levels;
+ super->s_total_levels = super->s_ifile_levels + super->s_iblock_levels
+ + super->s_data_levels;
+ page_cache_release(page);
+ return 0;
+}
+
+static int logfs_read_sb(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ int ret;
+
+ super->s_btree_pool = mempool_create(32, btree_alloc, btree_free, NULL);
+ if (!super->s_btree_pool)
+ return -ENOMEM;
+
+ btree_init_mempool64(&super->s_shadow_tree.new, super->s_btree_pool);
+ btree_init_mempool64(&super->s_shadow_tree.old, super->s_btree_pool);
+
+ ret = logfs_init_mapping(sb);
+ if (ret)
+ return ret;
+
+ ret = __logfs_read_sb(sb);
+ if (ret)
+ return ret;
+
+ mutex_init(&super->s_dirop_mutex);
+ mutex_init(&super->s_object_alias_mutex);
+ INIT_LIST_HEAD(&super->s_freeing_list);
+
+ ret = logfs_init_rw(sb);
+ if (ret)
+ return ret;
+
+ ret = logfs_init_areas(sb);
+ if (ret)
+ return ret;
+
+ ret = logfs_init_gc(sb);
+ if (ret)
+ return ret;
+
+ ret = logfs_init_journal(sb);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static void logfs_kill_sb(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+
+ log_super("LogFS: Start unmounting\n");
+ /* Alias entries slow down mount, so evict as many as possible */
+ sync_filesystem(sb);
+ logfs_write_anchor(super->s_master_inode);
+
+ /*
+ * From this point on alias entries are simply dropped - and any
+ * writes to the object store are considered bugs.
+ */
+ super->s_flags |= LOGFS_SB_FLAG_SHUTDOWN;
+ log_super("LogFS: Now in shutdown\n");
+ generic_shutdown_super(sb);
+
+ BUG_ON(super->s_dirty_used_bytes || super->s_dirty_free_bytes);
+
+ logfs_cleanup_gc(sb);
+ logfs_cleanup_journal(sb);
+ logfs_cleanup_areas(sb);
+ logfs_cleanup_rw(sb);
+ super->s_devops->put_device(sb);
+ mempool_destroy(super->s_btree_pool);
+ mempool_destroy(super->s_alias_pool);
+ kfree(super);
+ log_super("LogFS: Finished unmounting\n");
+}
+
+int logfs_get_sb_device(struct file_system_type *type, int flags,
+ struct mtd_info *mtd, struct block_device *bdev,
+ const struct logfs_device_ops *devops, struct vfsmount *mnt)
+{
+ struct logfs_super *super;
+ struct super_block *sb;
+ int err = -ENOMEM;
+ static int mount_count;
+
+ log_super("LogFS: Start mount %x\n", mount_count++);
+ super = kzalloc(sizeof(*super), GFP_KERNEL);
+ if (!super)
+ goto err0;
+
+ super->s_mtd = mtd;
+ super->s_bdev = bdev;
+ err = -EINVAL;
+ sb = sget(type, logfs_sb_test, logfs_sb_set, super);
+ if (IS_ERR(sb))
+ goto err0;
+
+ if (sb->s_root) {
+ /* Device is already in use */
+ err = 0;
+ simple_set_mnt(mnt, sb);
+ goto err0;
+ }
+
+ super->s_devops = devops;
+
+ /*
+ * sb->s_maxbytes is limited to 8TB. On 32bit systems, the page cache
+ * only covers 16TB and the upper 8TB are used for indirect blocks.
+ * On 64bit system we could bump up the limit, but that would make
+ * the filesystem incompatible with 32bit systems.
+ */
+ sb->s_maxbytes = (1ull << 43) - 1;
+ sb->s_op = &logfs_super_operations;
+ sb->s_flags = flags | MS_NOATIME;
+
+ err = logfs_read_sb(sb);
+ if (err)
+ goto err1;
+
+ sb->s_flags |= MS_ACTIVE;
+ err = logfs_get_sb_final(sb, mnt);
+ if (err)
+ goto err1;
+ return 0;
+
+err1:
+ up_write(&sb->s_umount);
+ deactivate_super(sb);
+ return err;
+err0:
+ kfree(super);
+ //devops->put_device(sb);
+ return err;
+}
+
+static int logfs_get_sb(struct file_system_type *type, int flags,
+ const char *devname, void *data, struct vfsmount *mnt)
+{
+ ulong mtdnr;
+
+ if (!devname)
+ return logfs_get_sb_bdev(type, flags, devname, mnt);
+ if (strncmp(devname, "mtd", 3))
+ return logfs_get_sb_bdev(type, flags, devname, mnt);
+
+ {
+ char *garbage;
+ mtdnr = simple_strtoul(devname+3, &garbage, 0);
+ if (*garbage)
+ return -EINVAL;
+ }
+
+ return logfs_get_sb_mtd(type, flags, mtdnr, mnt);
+}
+
+static struct file_system_type logfs_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "logfs",
+ .get_sb = logfs_get_sb,
+ .kill_sb = logfs_kill_sb,
+ .fs_flags = FS_REQUIRES_DEV,
+
+};
+
+static int __init logfs_init(void)
+{
+ int ret;
+
+ emergency_page = alloc_pages(GFP_KERNEL, 0);
+ if (!emergency_page)
+ return -ENOMEM;
+
+ ret = logfs_compr_init();
+ if (ret)
+ goto out1;
+
+ ret = logfs_init_inode_cache();
+ if (ret)
+ goto out2;
+
+ return register_filesystem(&logfs_fs_type);
+out2:
+ logfs_compr_exit();
+out1:
+ __free_pages(emergency_page, 0);
+ return ret;
+}
+
+static void __exit logfs_exit(void)
+{
+ unregister_filesystem(&logfs_fs_type);
+ logfs_destroy_inode_cache();
+ logfs_compr_exit();
+ __free_pages(emergency_page, 0);
+}
+
+module_init(logfs_init);
+module_exit(logfs_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Joern Engel <joern@logfs.org>");
+MODULE_DESCRIPTION("scalable flash filesystem");