[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/file.c b/fs/logfs/file.c
new file mode 100644
index 000000000000..370f367a933e
--- /dev/null
+++ b/fs/logfs/file.c
@@ -0,0 +1,263 @@
+/*
+ * fs/logfs/file.c      - prepare_write, commit_write and friends
+ *
+ * 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/sched.h>
+#include <linux/writeback.h>
+
+static int logfs_write_begin(struct file *file, struct address_space *mapping,
+                loff_t pos, unsigned len, unsigned flags,
+                struct page **pagep, void **fsdata)
+{
+        struct inode *inode = mapping->host;
+        struct page *page;
+        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+
+        page = grab_cache_page_write_begin(mapping, index, flags);
+        if (!page)
+                return -ENOMEM;
+        *pagep = page;
+
+        if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
+                return 0;
+        if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
+                unsigned start = pos & (PAGE_CACHE_SIZE - 1);
+                unsigned end = start + len;
+
+                /* Reading beyond i_size is simple: memset to zero */
+                zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
+                return 0;
+        }
+        return logfs_readpage_nolock(page);
+}
+
+static int logfs_write_end(struct file *file, struct address_space *mapping,
+                loff_t pos, unsigned len, unsigned copied, struct page *page,
+                void *fsdata)
+{
+        struct inode *inode = mapping->host;
+        pgoff_t index = page->index;
+        unsigned start = pos & (PAGE_CACHE_SIZE - 1);
+        unsigned end = start + copied;
+        int ret = 0;
+
+        BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize);
+        BUG_ON(page->index > I3_BLOCKS);
+
+        if (copied < len) {
+                /*
+                 * Short write of a non-initialized paged.  Just tell userspace
+                 * to retry the entire page.
+                 */
+                if (!PageUptodate(page)) {
+                        copied = 0;
+                        goto out;
+                }
+        }
+        if (copied == 0)
+                goto out; /* FIXME: do we need to update inode? */
+
+        if (i_size_read(inode) < (index << PAGE_CACHE_SHIFT) + end) {
+                i_size_write(inode, (index << PAGE_CACHE_SHIFT) + end);
+                mark_inode_dirty_sync(inode);
+        }
+
+        SetPageUptodate(page);
+        if (!PageDirty(page)) {
+                if (!get_page_reserve(inode, page))
+                        __set_page_dirty_nobuffers(page);
+                else
+                        ret = logfs_write_buf(inode, page, WF_LOCK);
+        }
+out:
+        unlock_page(page);
+        page_cache_release(page);
+        return ret ? ret : copied;
+}
+
+int logfs_readpage(struct file *file, struct page *page)
+{
+        int ret;
+
+        ret = logfs_readpage_nolock(page);
+        unlock_page(page);
+        return ret;
+}
+
+/* Clear the page's dirty flag in the radix tree. */
+/* TODO: mucking with PageWriteback is silly.  Add a generic function to clear
+ * the dirty bit from the radix tree for filesystems that don't have to wait
+ * for page writeback to finish (i.e. any compressing filesystem).
+ */
+static void clear_radix_tree_dirty(struct page *page)
+{
+        BUG_ON(PagePrivate(page) || page->private);
+        set_page_writeback(page);
+        end_page_writeback(page);
+}
+
+static int __logfs_writepage(struct page *page)
+{
+        struct inode *inode = page->mapping->host;
+        int err;
+
+        err = logfs_write_buf(inode, page, WF_LOCK);
+        if (err)
+                set_page_dirty(page);
+        else
+                clear_radix_tree_dirty(page);
+        unlock_page(page);
+        return err;
+}
+
+static int logfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+        struct inode *inode = page->mapping->host;
+        loff_t i_size = i_size_read(inode);
+        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+        unsigned offset;
+        u64 bix;
+        level_t level;
+
+        log_file("logfs_writepage(%lx, %lx, %p)\n", inode->i_ino, page->index,
+                        page);
+
+        logfs_unpack_index(page->index, &bix, &level);
+
+        /* Indirect blocks are never truncated */
+        if (level != 0)
+                return __logfs_writepage(page);
+
+        /*
+         * TODO: everything below is a near-verbatim copy of nobh_writepage().
+         * The relevant bits should be factored out after logfs is merged.
+         */
+
+        /* Is the page fully inside i_size? */
+        if (bix < end_index)
+                return __logfs_writepage(page);
+
+         /* Is the page fully outside i_size? (truncate in progress) */
+        offset = i_size & (PAGE_CACHE_SIZE-1);
+        if (bix > end_index || offset == 0) {
+                unlock_page(page);
+                return 0; /* don't care */
+        }
+
+        /*
+         * The page straddles i_size.  It must be zeroed out on each and every
+         * writepage invokation because it may be mmapped.  "A file is mapped
+         * in multiples of the page size.  For a file that is not a multiple of
+         * the  page size, the remaining memory is zeroed when mapped, and
+         * writes to that region are not written out to the file."
+         */
+        zero_user_segment(page, offset, PAGE_CACHE_SIZE);
+        return __logfs_writepage(page);
+}
+
+static void logfs_invalidatepage(struct page *page, unsigned long offset)
+{
+        move_page_to_btree(page);
+        BUG_ON(PagePrivate(page) || page->private);
+}
+
+static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this)
+{
+        return 0; /* None of these are easy to release */
+}
+
+
+int logfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+                unsigned long arg)
+{
+        struct logfs_inode *li = logfs_inode(inode);
+        unsigned int oldflags, flags;
+        int err;
+
+        switch (cmd) {
+        case FS_IOC_GETFLAGS:
+                flags = li->li_flags & LOGFS_FL_USER_VISIBLE;
+                return put_user(flags, (int __user *)arg);
+        case FS_IOC_SETFLAGS:
+                if (IS_RDONLY(inode))
+                        return -EROFS;
+
+                if (!is_owner_or_cap(inode))
+                        return -EACCES;
+
+                err = get_user(flags, (int __user *)arg);
+                if (err)
+                        return err;
+
+                mutex_lock(&inode->i_mutex);
+                oldflags = li->li_flags;
+                flags &= LOGFS_FL_USER_MODIFIABLE;
+                flags |= oldflags & ~LOGFS_FL_USER_MODIFIABLE;
+                li->li_flags = flags;
+                mutex_unlock(&inode->i_mutex);
+
+                inode->i_ctime = CURRENT_TIME;
+                mark_inode_dirty_sync(inode);
+                return 0;
+
+        default:
+                return -ENOTTY;
+        }
+}
+
+int logfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+        struct super_block *sb = dentry->d_inode->i_sb;
+        struct logfs_super *super = logfs_super(sb);
+
+        /* FIXME: write anchor */
+        super->s_devops->sync(sb);
+        return 0;
+}
+
+static int logfs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+        struct inode *inode = dentry->d_inode;
+        int err = 0;
+
+        if (attr->ia_valid & ATTR_SIZE)
+                err = logfs_truncate(inode, attr->ia_size);
+        attr->ia_valid &= ~ATTR_SIZE;
+
+        if (!err)
+                err = inode_change_ok(inode, attr);
+        if (!err)
+                err = inode_setattr(inode, attr);
+        return err;
+}
+
+const struct inode_operations logfs_reg_iops = {
+        .setattr        = logfs_setattr,
+};
+
+const struct file_operations logfs_reg_fops = {
+        .aio_read       = generic_file_aio_read,
+        .aio_write      = generic_file_aio_write,
+        .fsync          = logfs_fsync,
+        .ioctl          = logfs_ioctl,
+        .llseek         = generic_file_llseek,
+        .mmap           = generic_file_readonly_mmap,
+        .open           = generic_file_open,
+        .read           = do_sync_read,
+        .write          = do_sync_write,
+};
+
+const struct address_space_operations logfs_reg_aops = {
+        .invalidatepage = logfs_invalidatepage,
+        .readpage       = logfs_readpage,
+        .releasepage    = logfs_releasepage,
+        .set_page_dirty = __set_page_dirty_nobuffers,
+        .writepage      = logfs_writepage,
+        .writepages     = generic_writepages,
+        .write_begin    = logfs_write_begin,
+        .write_end      = logfs_write_end,
+};