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Subject[patch 13/15] fs/logfs/super.c
From
--- /dev/null	2008-04-02 16:29:12.813336657 +0200
+++ linux-2.6.24logfs/fs/logfs/super.c 2008-04-01 22:58:50.362878974 +0200
@@ -0,0 +1,374 @@
+/*
+ * fs/logfs/super.c
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2007 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 void dump_write(struct super_block *sb, int blockno, void *buf)
+{
+ struct logfs_super *super = logfs_super(sb);
+
+ if (blockno << sb->s_blocksize_bits >= super->s_segsize)
+ return;
+ super->s_devops->write(sb, blockno << sb->s_blocksize_bits,
+ sb->s_blocksize, buf);
+}
+
+/*
+ * 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)
+{
+ struct logfs_super *super = logfs_super(sb);
+ int i, blockno = 2, bs = sb->s_blocksize;
+ static char scratch[4096];
+ void *stack = (void *) ((ulong)current & ~0x1fffUL);
+
+ /* all wbufs */
+ if (super->s_writesize > 1)
+ for (i = 0; i < LOGFS_NO_AREAS; i++) {
+ void *wbuf = super->s_area[i]->a_wbuf;
+ u64 ofs = sb->s_blocksize + i*super->s_writesize;
+ super->s_devops->write(sb, ofs, super->s_writesize,
+ wbuf);
+ }
+ /* both superblocks */
+ memset(scratch, 0, bs);
+ memcpy(scratch, super, sizeof(*super));
+ memcpy(scratch + sizeof(*super) + 32, sb, sizeof(*sb));
+ dump_write(sb, blockno++, scratch);
+ /* process stack */
+ dump_write(sb, blockno++, stack);
+ dump_write(sb, blockno++, stack + 0x1000);
+}
+
+/*
+ * 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 ? super->s_mtd->mtd : NULL;
+ 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 ? super->s_mtd->mtd : NULL;
+
+ if (mtd && sb->s_mtd == mtd)
+ return 1;
+ if (super->s_bdev && sb->s_bdev == super->s_bdev)
+ return 1;
+ return 0;
+}
+
+static int logfs_make_writeable(struct super_block *sb)
+{
+ int err;
+
+ /* Check areas for trailing unaccounted data */
+ err = logfs_check_areas(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 = iget(sb, LOGFS_INO_ROOT);
+ if (!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 fail;
+
+ return simple_set_mnt(mnt, sb);
+
+fail:
+ iput(logfs_super(sb)->s_master_inode);
+ return -EIO;
+}
+
+static int logfs_read_sb(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_disk_super ds;
+ s64 ofs;
+ int i, ret;
+
+ ofs = super->s_devops->find_sb(sb);
+ if (ofs < 0)
+ return -EIO;
+ ret = super->s_devops->read(sb, ofs, sizeof(ds), &ds);
+ if (ret)
+ return ret;
+
+ if (be64_to_cpu(ds.ds_magic) != LOGFS_MAGIC)
+ return -EIO;
+
+ super->s_size = be64_to_cpu(ds.ds_filesystem_size);
+ super->s_root_reserve = be64_to_cpu(ds.ds_root_reserve);
+ super->s_segsize = 1 << ds.ds_segment_shift;
+ 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;
+
+ journal_for_each(i)
+ super->s_journal_seg[i] = be64_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;
+ super->s_gc_reserve = super->s_total_levels *
+ (2 * super->s_no_blocks - 1);
+ super->s_gc_reserve <<= sb->s_blocksize_bits;
+
+ mutex_init(&super->s_dirop_mutex);
+ spin_lock_init(&super->s_ino_lock);
+ INIT_LIST_HEAD(&super->s_freeing_list);
+
+ ret = logfs_init_rw(super);
+ if (ret)
+ return ret;
+
+ ret = logfs_init_areas(sb);
+ if (ret)
+ return ret;
+
+ ret = logfs_init_gc(super);
+ 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);
+
+ generic_shutdown_super(sb);
+
+ /* inode file is special and needs manual flushing */
+ logfs_flush_dirty(sb, 1);
+ BUG_ON(super->s_dirty_used_bytes || super->s_dirty_free_bytes);
+
+ logfs_cleanup_gc(super);
+ logfs_cleanup_journal(sb);
+ logfs_cleanup_areas(super);
+ logfs_cleanup_rw(super);
+ logfs_put_mtd(super->s_mtd);
+ logfs_put_bdev(super->s_bdev);
+ kfree(super);
+}
+
+int logfs_get_sb_device(struct file_system_type *type, int flags,
+ struct mtd_inode *mtd, struct block_device *bdev,
+ const struct logfs_device_ops *devops, struct vfsmount *mnt)
+{
+ struct logfs_super *super;
+ struct super_block *sb;
+ int i, err = -ENOMEM;
+
+ 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 = simple_set_mnt(mnt, sb);
+ goto err0;
+ }
+
+ super->s_devops = devops;
+ INIT_LIST_HEAD(&super->s_dirty_list);
+ for_each_area(i)
+ INIT_LIST_HEAD(&super->s_gc_dirty_list[i]);
+ /*
+ * Careful here. In principle s_maxbytes could easily be bumped up to
+ * LOGFS_I5_SIZE. Most of the code just needs a thorough audit and
+ * a couple of changes to allow for 4x and 5x indirect blocks.
+ *
+ * There is one detail requiring a little more care, though:
+ * As we use the upper half of each file's address space for metadata,
+ * s_maxbytes must remain below LONG_MAX. Which means a different
+ * limit on 64bit and 32bit systems and potentially files created on
+ * one system that cannot be fully read on another.
+ *
+ * LOGFS_I3_SIZE is below 8TB, which is a safe choice for now.
+ */
+ sb->s_maxbytes = LOGFS_I3_SIZE;
+ 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);
+ logfs_put_mtd(mtd);
+ logfs_put_bdev(bdev);
+ 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,
+};
+
+static int __init logfs_init(void)
+{
+ int ret;
+
+ ret = logfs_compr_init();
+ if (ret)
+ return ret;
+
+ ret = logfs_init_inode_cache();
+ if (ret) {
+ logfs_compr_exit();
+ return ret;
+ }
+
+ return register_filesystem(&logfs_fs_type);
+}
+
+static void __exit logfs_exit(void)
+{
+ unregister_filesystem(&logfs_fs_type);
+ logfs_destroy_inode_cache();
+ logfs_compr_exit();
+}
+
+module_init(logfs_init);
+module_exit(logfs_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Joern Engel <joern@logfs.org>");
+MODULE_DESCRIPTION("scalable flash filesystem");


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