--- /dev/null 2007-08-05 21:14:35.622844160 +0200
+++ linux-2.6.21logfs/fs/logfs/file.c 2007-08-08 02:57:37.000000000 +0200
@@ -0,0 +1,176 @@
+/*
+ * fs/logfs/file.c - prepare_write, commit_write and friends
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2007 Joern Engel <joern@xxxxxxxxx>
+ */
+#include "logfs.h"
+
+static int logfs_prepare_write(struct file *file, struct page *page,
+ unsigned start, unsigned end)
+{
+ if (PageUptodate(page))
+ return 0;
+
+ if ((start == 0) && (end == PAGE_CACHE_SIZE))
+ return 0;
+
+ return logfs_readpage_nolock(page);
+}
+
+static int logfs_commit_write(struct file *file, struct page *page,
+ unsigned start, unsigned end)
+{
+ struct inode *inode = page->mapping->host;
+ pgoff_t index = page->index;
+ void *buf;
+ int ret;
+
+ BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize);
+ BUG_ON(page->index > I3_BLOCKS);
+
+ if (start == end)
+ return 0; /* 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);
+ }
+
+ buf = kmap(page);
+ ret = logfs_write_buf(inode, index, buf, 1, NULL);
+ kunmap(page);
+ return ret;
+}
+
+static int logfs_readpage(struct file *file, struct page *page)
+{
+ int ret;
+
+ ret = logfs_readpage_nolock(page);
+ unlock_page(page);
+ return ret;
+}
+
+static int __logfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ pgoff_t index = page->index;
+ void *buf;
+ int ret;
+
+ buf = kmap(page);
+ ret = logfs_write_buf(inode, index, buf, 1, NULL);
+ kunmap(page);
+ unlock_page(page);
+ return ret;
+}
+
+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;
+ void *buf;
+
+ /* Write full page */
+ if (page->index < end_index)
+ return __logfs_writepage(page, wbc);
+
+ offset = i_size & (PAGE_CACHE_SIZE-1);
+ if (page->index > end_index || offset == 0) {
+ /*
+ * I believe this case cannot happen, therefore the BUG. If
+ * this doesn't trigger for a year or so or someone explains
+ * the code to me, I'll remove the branch completely.
+ */
+ BUG();
+ do_invalidatepage(page, 0);
+ unlock_page(page);
+ return 0;
+ }
+ /* Write partial page, must clear the rest */
+ buf = kmap_atomic(page, KM_USER0);
+ memset(buf + offset, 0, PAGE_CACHE_SIZE - offset);
+ flush_dcache_page(page);
+ kunmap_atomic(page, KM_USER0);
+ return __logfs_writepage(page, wbc);
+}
+
+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 ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
+ 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 inode *inode = dentry->d_inode;
+ struct logfs_super *super = logfs_super(inode->i_sb);
+ int err;
+
+ err = __logfs_write_inode(inode, 1);
+ if (err)
+ return err;
+
+ super->s_devops->sync(inode->i_sb);
+ return 0;
+}
+
+const struct inode_operations logfs_reg_iops = {
+ .truncate = logfs_truncate,
+};
+
+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 = {
+ .commit_write = logfs_commit_write,
+ .prepare_write = logfs_prepare_write,
+ .readpage = logfs_readpage,
+ .set_page_dirty = __set_page_dirty_nobuffers,
+ .writepage = logfs_writepage,
+};
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