[LogFS] add new flash file system

This is a new flash file system. See
Documentation/filesystems/logfs.txt

Signed-off-by: Joern Engel <joern@logfs.org>

1 files changed, 263 insertions, 0 deletions

diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c
new file mode 100644
index 000000000000..58a057b6e1af
--- /dev/null
+++ b/fs/logfs/dev_bdev.c
@@ -0,0 +1,263 @@
+/*
+ * fs/logfs/dev_bdev.c  - Device access methods for block devices
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
+ */
+#include "logfs.h"
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+
+#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
+
+static void request_complete(struct bio *bio, int err)
+{
+        complete((struct completion *)bio->bi_private);
+}
+
+static int sync_request(struct page *page, struct block_device *bdev, int rw)
+{
+        struct bio bio;
+        struct bio_vec bio_vec;
+        struct completion complete;
+
+        bio_init(&bio);
+        bio.bi_io_vec = &bio_vec;
+        bio_vec.bv_page = page;
+        bio_vec.bv_len = PAGE_SIZE;
+        bio_vec.bv_offset = 0;
+        bio.bi_vcnt = 1;
+        bio.bi_idx = 0;
+        bio.bi_size = PAGE_SIZE;
+        bio.bi_bdev = bdev;
+        bio.bi_sector = page->index * (PAGE_SIZE >> 9);
+        init_completion(&complete);
+        bio.bi_private = &complete;
+        bio.bi_end_io = request_complete;
+
+        submit_bio(rw, &bio);
+        generic_unplug_device(bdev_get_queue(bdev));
+        wait_for_completion(&complete);
+        return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO;
+}
+
+static int bdev_readpage(void *_sb, struct page *page)
+{
+        struct super_block *sb = _sb;
+        struct block_device *bdev = logfs_super(sb)->s_bdev;
+        int err;
+
+        err = sync_request(page, bdev, READ);
+        if (err) {
+                ClearPageUptodate(page);
+                SetPageError(page);
+        } else {
+                SetPageUptodate(page);
+                ClearPageError(page);
+        }
+        unlock_page(page);
+        return err;
+}
+
+static DECLARE_WAIT_QUEUE_HEAD(wq);
+
+static void writeseg_end_io(struct bio *bio, int err)
+{
+        const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+        struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+        struct super_block *sb = bio->bi_private;
+        struct logfs_super *super = logfs_super(sb);
+        struct page *page;
+
+        BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
+        BUG_ON(err);
+        BUG_ON(bio->bi_vcnt == 0);
+        do {
+                page = bvec->bv_page;
+                if (--bvec >= bio->bi_io_vec)
+                        prefetchw(&bvec->bv_page->flags);
+
+                end_page_writeback(page);
+        } while (bvec >= bio->bi_io_vec);
+        bio_put(bio);
+        if (atomic_dec_and_test(&super->s_pending_writes))
+                wake_up(&wq);
+}
+
+static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
+                size_t nr_pages)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct address_space *mapping = super->s_mapping_inode->i_mapping;
+        struct bio *bio;
+        struct page *page;
+        struct request_queue *q = bdev_get_queue(sb->s_bdev);
+        unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
+        int i;
+
+        bio = bio_alloc(GFP_NOFS, max_pages);
+        BUG_ON(!bio); /* FIXME: handle this */
+
+        for (i = 0; i < nr_pages; i++) {
+                if (i >= max_pages) {
+                        /* Block layer cannot split bios :( */
+                        bio->bi_vcnt = i;
+                        bio->bi_idx = 0;
+                        bio->bi_size = i * PAGE_SIZE;
+                        bio->bi_bdev = super->s_bdev;
+                        bio->bi_sector = ofs >> 9;
+                        bio->bi_private = sb;
+                        bio->bi_end_io = writeseg_end_io;
+                        atomic_inc(&super->s_pending_writes);
+                        submit_bio(WRITE, bio);
+
+                        ofs += i * PAGE_SIZE;
+                        index += i;
+                        nr_pages -= i;
+                        i = 0;
+
+                        bio = bio_alloc(GFP_NOFS, max_pages);
+                        BUG_ON(!bio);
+                }
+                page = find_lock_page(mapping, index + i);
+                BUG_ON(!page);
+                bio->bi_io_vec[i].bv_page = page;
+                bio->bi_io_vec[i].bv_len = PAGE_SIZE;
+                bio->bi_io_vec[i].bv_offset = 0;
+
+                BUG_ON(PageWriteback(page));
+                set_page_writeback(page);
+                unlock_page(page);
+        }
+        bio->bi_vcnt = nr_pages;
+        bio->bi_idx = 0;
+        bio->bi_size = nr_pages * PAGE_SIZE;
+        bio->bi_bdev = super->s_bdev;
+        bio->bi_sector = ofs >> 9;
+        bio->bi_private = sb;
+        bio->bi_end_io = writeseg_end_io;
+        atomic_inc(&super->s_pending_writes);
+        submit_bio(WRITE, bio);
+        return 0;
+}
+
+static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len)
+{
+        struct logfs_super *super = logfs_super(sb);
+        int head;
+
+        BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO);
+
+        if (len == 0) {
+                /* This can happen when the object fit perfectly into a
+                 * segment, the segment gets written per sync and subsequently
+                 * closed.
+                 */
+                return;
+        }
+        head = ofs & (PAGE_SIZE - 1);
+        if (head) {
+                ofs -= head;
+                len += head;
+        }
+        len = PAGE_ALIGN(len);
+        __bdev_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
+        generic_unplug_device(bdev_get_queue(logfs_super(sb)->s_bdev));
+}
+
+static int bdev_erase(struct super_block *sb, loff_t to, size_t len)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct address_space *mapping = super->s_mapping_inode->i_mapping;
+        struct page *page;
+        pgoff_t index = to >> PAGE_SHIFT;
+        int i, nr_pages = len >> PAGE_SHIFT;
+
+        BUG_ON(to & (PAGE_SIZE - 1));
+        BUG_ON(len & (PAGE_SIZE - 1));
+
+        if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO)
+                return -EROFS;
+
+        for (i = 0; i < nr_pages; i++) {
+                page = find_get_page(mapping, index + i);
+                if (page) {
+                        memset(page_address(page), 0xFF, PAGE_SIZE);
+                        page_cache_release(page);
+                }
+        }
+        return 0;
+}
+
+static void bdev_sync(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+
+        wait_event(wq, atomic_read(&super->s_pending_writes) == 0);
+}
+
+static struct page *bdev_find_first_sb(struct super_block *sb, u64 *ofs)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct address_space *mapping = super->s_mapping_inode->i_mapping;
+        filler_t *filler = bdev_readpage;
+
+        *ofs = 0;
+        return read_cache_page(mapping, 0, filler, sb);
+}
+
+static struct page *bdev_find_last_sb(struct super_block *sb, u64 *ofs)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct address_space *mapping = super->s_mapping_inode->i_mapping;
+        filler_t *filler = bdev_readpage;
+        u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000;
+        pgoff_t index = pos >> PAGE_SHIFT;
+
+        *ofs = pos;
+        return read_cache_page(mapping, index, filler, sb);
+}
+
+static int bdev_write_sb(struct super_block *sb, struct page *page)
+{
+        struct block_device *bdev = logfs_super(sb)->s_bdev;
+
+        /* Nothing special to do for block devices. */
+        return sync_request(page, bdev, WRITE);
+}
+
+static void bdev_put_device(struct super_block *sb)
+{
+        close_bdev_exclusive(logfs_super(sb)->s_bdev, FMODE_READ|FMODE_WRITE);
+}
+
+static const struct logfs_device_ops bd_devops = {
+        .find_first_sb  = bdev_find_first_sb,
+        .find_last_sb   = bdev_find_last_sb,
+        .write_sb       = bdev_write_sb,
+        .readpage       = bdev_readpage,
+        .writeseg       = bdev_writeseg,
+        .erase          = bdev_erase,
+        .sync           = bdev_sync,
+        .put_device     = bdev_put_device,
+};
+
+int logfs_get_sb_bdev(struct file_system_type *type, int flags,
+                const char *devname, struct vfsmount *mnt)
+{
+        struct block_device *bdev;
+
+        bdev = open_bdev_exclusive(devname, FMODE_READ|FMODE_WRITE, type);
+        if (IS_ERR(bdev))
+                return PTR_ERR(bdev);
+
+        if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
+                int mtdnr = MINOR(bdev->bd_dev);
+                close_bdev_exclusive(bdev, FMODE_READ|FMODE_WRITE);
+                return logfs_get_sb_mtd(type, flags, mtdnr, mnt);
+        }
+
+        return logfs_get_sb_device(type, flags, NULL, bdev, &bd_devops, mnt);
+}