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Subject[patch 14/15] fs/logfs/dev_bdev.c
From
--- /dev/null	2008-03-30 12:15:48.586669308 +0200
+++ linux-2.6.24logfs/fs/logfs/dev_bdev.c 2008-03-28 20:04:13.961033452 +0100
@@ -0,0 +1,146 @@
+/*
+ * fs/logfs/dev_bdev.c - Device access methods for block devices
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2007 Joern Engel <joern@logfs.org>
+ */
+#include "logfs.h"
+#include <linux/buffer_head.h>
+
+#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
+
+static int bdev_read(struct super_block *sb, loff_t from, size_t len, void *buf)
+{
+ struct block_device *bdev = logfs_super(sb)->s_bdev;
+ struct address_space *mapping = bdev->bd_inode->i_mapping;
+ struct page *page;
+ long index = from >> PAGE_SHIFT;
+ long offset = from & (PAGE_SIZE-1);
+ long copylen;
+
+ while (len) {
+ copylen = min((ulong)len, PAGE_SIZE - offset);
+
+ page = read_cache_page(mapping, index,
+ (filler_t *)mapping->a_ops->readpage, NULL);
+ if (!page)
+ return -ENOMEM;
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+
+ memcpy(buf, page_address(page) + offset, copylen);
+ page_cache_release(page);
+
+ buf += copylen;
+ len -= copylen;
+ offset = 0;
+ index++;
+ }
+ return 0;
+}
+
+static int bdev_write(struct super_block *sb, loff_t to, size_t len, void *buf)
+{
+ struct block_device *bdev = logfs_super(sb)->s_bdev;
+ struct address_space *mapping = bdev->bd_inode->i_mapping;
+ struct page *page;
+ long index = to >> PAGE_SHIFT;
+ long offset = to & (PAGE_SIZE-1);
+ long copylen;
+
+ if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO)
+ return -EROFS;
+
+ while (len) {
+ copylen = min((ulong)len, PAGE_SIZE - offset);
+
+ page = read_cache_page(mapping, index,
+ (filler_t *)mapping->a_ops->readpage, NULL);
+ if (!page)
+ return -ENOMEM;
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+ lock_page(page);
+ memcpy(page_address(page) + offset, buf, copylen);
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+
+ buf += copylen;
+ len -= copylen;
+ offset = 0;
+ index++;
+ }
+ return 0;
+}
+
+static int bdev_erase(struct super_block *sb, loff_t to, size_t len)
+{
+ struct block_device *bdev = logfs_super(sb)->s_bdev;
+ struct address_space *mapping = bdev->bd_inode->i_mapping;
+ struct page *page;
+ long index = to >> PAGE_SHIFT;
+ long offset = to & (PAGE_SIZE-1);
+ long copylen;
+
+ if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO)
+ return -EROFS;
+
+ while (len) {
+ copylen = min((ulong)len, PAGE_SIZE - offset);
+
+ page = read_cache_page(mapping, index,
+ (filler_t *)mapping->a_ops->readpage, NULL);
+ if (!page)
+ return -ENOMEM;
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+ lock_page(page);
+ memset(page_address(page) + offset, 0xFF, copylen);
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+
+ len -= copylen;
+ offset = 0;
+ index++;
+ }
+ return 0;
+}
+
+static void bdev_sync(struct super_block *sb)
+{
+ sync_blockdev(logfs_super(sb)->s_bdev);
+}
+
+static s64 bdev_find_sb(struct super_block *sb)
+{
+ return 0;
+}
+
+static const struct logfs_device_ops bd_devops = {
+ .find_sb = bdev_find_sb,
+ .read = bdev_read,
+ .write = bdev_write,
+ .erase = bdev_erase,
+ .sync = bdev_sync,
+};
+
+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_excl(devname, O_RDWR, NULL);
+ if (IS_ERR(bdev))
+ return PTR_ERR(bdev);
+
+ if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
+ int mtdnr = MINOR(bdev->bd_dev);
+ close_bdev_excl(bdev);
+ return logfs_get_sb_mtd(type, flags, mtdnr, mnt);
+ }
+
+ return logfs_get_sb_device(type, flags, NULL, bdev, &bd_devops, mnt);
+}


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