Btrfs: split up super.c
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
new file mode 100644
index 0000000..7f8e303
--- /dev/null
+++ b/fs/btrfs/file.c
@@ -0,0 +1,783 @@
+#include <linux/module.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+#include <linux/mpage.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/statfs.h>
+#include <linux/compat.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "ioctl.h"
+#include "print-tree.h"
+
+
+static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
+ struct page **prepared_pages,
+ const char __user * buf)
+{
+ long page_fault = 0;
+ int i;
+ int offset = pos & (PAGE_CACHE_SIZE - 1);
+
+ for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
+ size_t count = min_t(size_t,
+ PAGE_CACHE_SIZE - offset, write_bytes);
+ struct page *page = prepared_pages[i];
+ fault_in_pages_readable(buf, count);
+
+ /* Copy data from userspace to the current page */
+ kmap(page);
+ page_fault = __copy_from_user(page_address(page) + offset,
+ buf, count);
+ /* Flush processor's dcache for this page */
+ flush_dcache_page(page);
+ kunmap(page);
+ buf += count;
+ write_bytes -= count;
+
+ if (page_fault)
+ break;
+ }
+ return page_fault ? -EFAULT : 0;
+}
+
+static void btrfs_drop_pages(struct page **pages, size_t num_pages)
+{
+ size_t i;
+ for (i = 0; i < num_pages; i++) {
+ if (!pages[i])
+ break;
+ unlock_page(pages[i]);
+ mark_page_accessed(pages[i]);
+ page_cache_release(pages[i]);
+ }
+}
+
+static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct file *file,
+ struct page **pages,
+ size_t num_pages,
+ loff_t pos,
+ size_t write_bytes)
+{
+ int i;
+ int offset;
+ int err = 0;
+ int ret;
+ int this_write;
+ struct inode *inode = file->f_path.dentry->d_inode;
+ struct buffer_head *bh;
+ struct btrfs_file_extent_item *ei;
+
+ for (i = 0; i < num_pages; i++) {
+ offset = pos & (PAGE_CACHE_SIZE -1);
+ this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
+ /* FIXME, one block at a time */
+
+ mutex_lock(&root->fs_info->fs_mutex);
+ trans = btrfs_start_transaction(root, 1);
+ btrfs_set_trans_block_group(trans, inode);
+
+ bh = page_buffers(pages[i]);
+
+ if (buffer_mapped(bh) && bh->b_blocknr == 0) {
+ struct btrfs_key key;
+ struct btrfs_path *path;
+ char *ptr;
+ u32 datasize;
+
+ /* create an inline extent, and copy the data in */
+ path = btrfs_alloc_path();
+ BUG_ON(!path);
+ key.objectid = inode->i_ino;
+ key.offset = pages[i]->index << PAGE_CACHE_SHIFT;
+ key.flags = 0;
+ btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
+ BUG_ON(write_bytes >= PAGE_CACHE_SIZE);
+ datasize = offset +
+ btrfs_file_extent_calc_inline_size(write_bytes);
+
+ ret = btrfs_insert_empty_item(trans, root, path, &key,
+ datasize);
+ BUG_ON(ret);
+ ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
+ path->slots[0], struct btrfs_file_extent_item);
+ btrfs_set_file_extent_generation(ei, trans->transid);
+ btrfs_set_file_extent_type(ei,
+ BTRFS_FILE_EXTENT_INLINE);
+ ptr = btrfs_file_extent_inline_start(ei);
+ btrfs_memcpy(root, path->nodes[0]->b_data,
+ ptr, bh->b_data, offset + write_bytes);
+ mark_buffer_dirty(path->nodes[0]);
+ btrfs_free_path(path);
+ } else if (buffer_mapped(bh)) {
+ /* csum the file data */
+ btrfs_csum_file_block(trans, root, inode->i_ino,
+ pages[i]->index << PAGE_CACHE_SHIFT,
+ kmap(pages[i]), PAGE_CACHE_SIZE);
+ kunmap(pages[i]);
+ }
+ SetPageChecked(pages[i]);
+ ret = btrfs_end_transaction(trans, root);
+ BUG_ON(ret);
+ mutex_unlock(&root->fs_info->fs_mutex);
+
+ ret = btrfs_commit_write(file, pages[i], offset,
+ offset + this_write);
+ pos += this_write;
+ if (ret) {
+ err = ret;
+ goto failed;
+ }
+ WARN_ON(this_write > write_bytes);
+ write_bytes -= this_write;
+ }
+failed:
+ return err;
+}
+
+/*
+ * this is very complex, but the basic idea is to drop all extents
+ * in the range start - end. hint_block is filled in with a block number
+ * that would be a good hint to the block allocator for this file.
+ *
+ * If an extent intersects the range but is not entirely inside the range
+ * it is either truncated or split. Anything entirely inside the range
+ * is deleted from the tree.
+ */
+int btrfs_drop_extents(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, struct inode *inode,
+ u64 start, u64 end, u64 *hint_block)
+{
+ int ret;
+ struct btrfs_key key;
+ struct btrfs_leaf *leaf;
+ int slot;
+ struct btrfs_file_extent_item *extent;
+ u64 extent_end = 0;
+ int keep;
+ struct btrfs_file_extent_item old;
+ struct btrfs_path *path;
+ u64 search_start = start;
+ int bookend;
+ int found_type;
+ int found_extent;
+ int found_inline;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ while(1) {
+ btrfs_release_path(root, path);
+ ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
+ search_start, -1);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ if (path->slots[0] == 0) {
+ ret = 0;
+ goto out;
+ }
+ path->slots[0]--;
+ }
+ keep = 0;
+ bookend = 0;
+ found_extent = 0;
+ found_inline = 0;
+ extent = NULL;
+ leaf = btrfs_buffer_leaf(path->nodes[0]);
+ slot = path->slots[0];
+ btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
+ if (key.offset >= end || key.objectid != inode->i_ino) {
+ ret = 0;
+ goto out;
+ }
+ if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY) {
+ ret = 0;
+ goto out;
+ }
+ extent = btrfs_item_ptr(leaf, slot,
+ struct btrfs_file_extent_item);
+ found_type = btrfs_file_extent_type(extent);
+ if (found_type == BTRFS_FILE_EXTENT_REG) {
+ extent_end = key.offset +
+ (btrfs_file_extent_num_blocks(extent) <<
+ inode->i_blkbits);
+ found_extent = 1;
+ } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+ found_inline = 1;
+ extent_end = key.offset +
+ btrfs_file_extent_inline_len(leaf->items + slot);
+ }
+
+ /* we found nothing we can drop */
+ if (!found_extent && !found_inline) {
+ ret = 0;
+ goto out;
+ }
+
+ /* we found nothing inside the range */
+ if (search_start >= extent_end) {
+ ret = 0;
+ goto out;
+ }
+
+ /* FIXME, there's only one inline extent allowed right now */
+ if (found_inline) {
+ u64 mask = root->blocksize - 1;
+ search_start = (extent_end + mask) & ~mask;
+ } else
+ search_start = extent_end;
+
+ if (end < extent_end && end >= key.offset) {
+ if (found_extent) {
+ u64 disk_blocknr =
+ btrfs_file_extent_disk_blocknr(extent);
+ u64 disk_num_blocks =
+ btrfs_file_extent_disk_num_blocks(extent);
+ memcpy(&old, extent, sizeof(old));
+ if (disk_blocknr != 0) {
+ ret = btrfs_inc_extent_ref(trans, root,
+ disk_blocknr, disk_num_blocks);
+ BUG_ON(ret);
+ }
+ }
+ WARN_ON(found_inline);
+ bookend = 1;
+ }
+
+ /* truncate existing extent */
+ if (start > key.offset) {
+ u64 new_num;
+ u64 old_num;
+ keep = 1;
+ WARN_ON(start & (root->blocksize - 1));
+ if (found_extent) {
+ new_num = (start - key.offset) >>
+ inode->i_blkbits;
+ old_num = btrfs_file_extent_num_blocks(extent);
+ *hint_block =
+ btrfs_file_extent_disk_blocknr(extent);
+ if (btrfs_file_extent_disk_blocknr(extent)) {
+ inode->i_blocks -=
+ (old_num - new_num) << 3;
+ }
+ btrfs_set_file_extent_num_blocks(extent,
+ new_num);
+ mark_buffer_dirty(path->nodes[0]);
+ } else {
+ WARN_ON(1);
+ }
+ }
+ /* delete the entire extent */
+ if (!keep) {
+ u64 disk_blocknr = 0;
+ u64 disk_num_blocks = 0;
+ u64 extent_num_blocks = 0;
+ if (found_extent) {
+ disk_blocknr =
+ btrfs_file_extent_disk_blocknr(extent);
+ disk_num_blocks =
+ btrfs_file_extent_disk_num_blocks(extent);
+ extent_num_blocks =
+ btrfs_file_extent_num_blocks(extent);
+ *hint_block =
+ btrfs_file_extent_disk_blocknr(extent);
+ }
+ ret = btrfs_del_item(trans, root, path);
+ BUG_ON(ret);
+ btrfs_release_path(root, path);
+ extent = NULL;
+ if (found_extent && disk_blocknr != 0) {
+ inode->i_blocks -= extent_num_blocks << 3;
+ ret = btrfs_free_extent(trans, root,
+ disk_blocknr,
+ disk_num_blocks, 0);
+ }
+
+ BUG_ON(ret);
+ if (!bookend && search_start >= end) {
+ ret = 0;
+ goto out;
+ }
+ if (!bookend)
+ continue;
+ }
+ /* create bookend, splitting the extent in two */
+ if (bookend && found_extent) {
+ struct btrfs_key ins;
+ ins.objectid = inode->i_ino;
+ ins.offset = end;
+ ins.flags = 0;
+ btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
+
+ btrfs_release_path(root, path);
+ ret = btrfs_insert_empty_item(trans, root, path, &ins,
+ sizeof(*extent));
+ BUG_ON(ret);
+ extent = btrfs_item_ptr(
+ btrfs_buffer_leaf(path->nodes[0]),
+ path->slots[0],
+ struct btrfs_file_extent_item);
+ btrfs_set_file_extent_disk_blocknr(extent,
+ btrfs_file_extent_disk_blocknr(&old));
+ btrfs_set_file_extent_disk_num_blocks(extent,
+ btrfs_file_extent_disk_num_blocks(&old));
+
+ btrfs_set_file_extent_offset(extent,
+ btrfs_file_extent_offset(&old) +
+ ((end - key.offset) >> inode->i_blkbits));
+ WARN_ON(btrfs_file_extent_num_blocks(&old) <
+ (extent_end - end) >> inode->i_blkbits);
+ btrfs_set_file_extent_num_blocks(extent,
+ (extent_end - end) >> inode->i_blkbits);
+
+ btrfs_set_file_extent_type(extent,
+ BTRFS_FILE_EXTENT_REG);
+ btrfs_set_file_extent_generation(extent,
+ btrfs_file_extent_generation(&old));
+ btrfs_mark_buffer_dirty(path->nodes[0]);
+ if (btrfs_file_extent_disk_blocknr(&old) != 0) {
+ inode->i_blocks +=
+ btrfs_file_extent_num_blocks(extent) << 3;
+ }
+ ret = 0;
+ goto out;
+ }
+ }
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+/*
+ * this gets pages into the page cache and locks them down
+ */
+static int prepare_pages(struct btrfs_root *root,
+ struct file *file,
+ struct page **pages,
+ size_t num_pages,
+ loff_t pos,
+ unsigned long first_index,
+ unsigned long last_index,
+ size_t write_bytes,
+ u64 alloc_extent_start)
+{
+ int i;
+ unsigned long index = pos >> PAGE_CACHE_SHIFT;
+ struct inode *inode = file->f_path.dentry->d_inode;
+ int offset;
+ int err = 0;
+ int this_write;
+ struct buffer_head *bh;
+ struct buffer_head *head;
+ loff_t isize = i_size_read(inode);
+
+ memset(pages, 0, num_pages * sizeof(struct page *));
+
+ for (i = 0; i < num_pages; i++) {
+ pages[i] = grab_cache_page(inode->i_mapping, index + i);
+ if (!pages[i]) {
+ err = -ENOMEM;
+ goto failed_release;
+ }
+ cancel_dirty_page(pages[i], PAGE_CACHE_SIZE);
+ wait_on_page_writeback(pages[i]);
+ offset = pos & (PAGE_CACHE_SIZE -1);
+ this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
+ if (!page_has_buffers(pages[i])) {
+ create_empty_buffers(pages[i],
+ root->fs_info->sb->s_blocksize,
+ (1 << BH_Uptodate));
+ }
+ head = page_buffers(pages[i]);
+ bh = head;
+ do {
+ err = btrfs_map_bh_to_logical(root, bh,
+ alloc_extent_start);
+ BUG_ON(err);
+ if (err)
+ goto failed_truncate;
+ bh = bh->b_this_page;
+ if (alloc_extent_start)
+ alloc_extent_start++;
+ } while (bh != head);
+ pos += this_write;
+ WARN_ON(this_write > write_bytes);
+ write_bytes -= this_write;
+ }
+ return 0;
+
+failed_release:
+ btrfs_drop_pages(pages, num_pages);
+ return err;
+
+failed_truncate:
+ btrfs_drop_pages(pages, num_pages);
+ if (pos > isize)
+ vmtruncate(inode, isize);
+ return err;
+}
+
+static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ loff_t pos;
+ size_t num_written = 0;
+ int err = 0;
+ int ret = 0;
+ struct inode *inode = file->f_path.dentry->d_inode;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct page *pages[8];
+ struct page *pinned[2];
+ unsigned long first_index;
+ unsigned long last_index;
+ u64 start_pos;
+ u64 num_blocks;
+ u64 alloc_extent_start;
+ u64 hint_block;
+ struct btrfs_trans_handle *trans;
+ struct btrfs_key ins;
+ pinned[0] = NULL;
+ pinned[1] = NULL;
+ if (file->f_flags & O_DIRECT)
+ return -EINVAL;
+ pos = *ppos;
+ vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+ current->backing_dev_info = inode->i_mapping->backing_dev_info;
+ err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
+ if (err)
+ goto out;
+ if (count == 0)
+ goto out;
+ err = remove_suid(file->f_path.dentry);
+ if (err)
+ goto out;
+ file_update_time(file);
+
+ start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);
+ num_blocks = (count + pos - start_pos + root->blocksize - 1) >>
+ inode->i_blkbits;
+
+ mutex_lock(&inode->i_mutex);
+ first_index = pos >> PAGE_CACHE_SHIFT;
+ last_index = (pos + count) >> PAGE_CACHE_SHIFT;
+
+ /*
+ * there are lots of better ways to do this, but this code
+ * makes sure the first and last page in the file range are
+ * up to date and ready for cow
+ */
+ if ((pos & (PAGE_CACHE_SIZE - 1))) {
+ pinned[0] = grab_cache_page(inode->i_mapping, first_index);
+ if (!PageUptodate(pinned[0])) {
+ ret = mpage_readpage(pinned[0], btrfs_get_block);
+ BUG_ON(ret);
+ wait_on_page_locked(pinned[0]);
+ } else {
+ unlock_page(pinned[0]);
+ }
+ }
+ if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
+ pinned[1] = grab_cache_page(inode->i_mapping, last_index);
+ if (!PageUptodate(pinned[1])) {
+ ret = mpage_readpage(pinned[1], btrfs_get_block);
+ BUG_ON(ret);
+ wait_on_page_locked(pinned[1]);
+ } else {
+ unlock_page(pinned[1]);
+ }
+ }
+
+ mutex_lock(&root->fs_info->fs_mutex);
+ trans = btrfs_start_transaction(root, 1);
+ if (!trans) {
+ err = -ENOMEM;
+ mutex_unlock(&root->fs_info->fs_mutex);
+ goto out_unlock;
+ }
+ btrfs_set_trans_block_group(trans, inode);
+ /* FIXME blocksize != 4096 */
+ inode->i_blocks += num_blocks << 3;
+ hint_block = 0;
+
+ /* FIXME...EIEIO, ENOSPC and more */
+
+ /* step one, delete the existing extents in this range */
+ if (start_pos < inode->i_size) {
+ /* FIXME blocksize != pagesize */
+ ret = btrfs_drop_extents(trans, root, inode,
+ start_pos,
+ (pos + count + root->blocksize -1) &
+ ~((u64)root->blocksize - 1),
+ &hint_block);
+ BUG_ON(ret);
+ }
+
+ /* insert any holes we need to create */
+ if (inode->i_size < start_pos) {
+ u64 last_pos_in_file;
+ u64 hole_size;
+ u64 mask = root->blocksize - 1;
+ last_pos_in_file = (inode->i_size + mask) & ~mask;
+ hole_size = (start_pos - last_pos_in_file + mask) & ~mask;
+ hole_size >>= inode->i_blkbits;
+ if (last_pos_in_file < start_pos) {
+ ret = btrfs_insert_file_extent(trans, root,
+ inode->i_ino,
+ last_pos_in_file,
+ 0, 0, hole_size);
+ }
+ BUG_ON(ret);
+ }
+
+ /*
+ * either allocate an extent for the new bytes or setup the key
+ * to show we are doing inline data in the extent
+ */
+ if (inode->i_size >= PAGE_CACHE_SIZE || pos + count < inode->i_size ||
+ pos + count - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
+ ret = btrfs_alloc_extent(trans, root, inode->i_ino,
+ num_blocks, hint_block, (u64)-1,
+ &ins, 1);
+ BUG_ON(ret);
+ ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
+ start_pos, ins.objectid, ins.offset,
+ ins.offset);
+ BUG_ON(ret);
+ } else {
+ ins.offset = 0;
+ ins.objectid = 0;
+ }
+ BUG_ON(ret);
+ alloc_extent_start = ins.objectid;
+ ret = btrfs_end_transaction(trans, root);
+ mutex_unlock(&root->fs_info->fs_mutex);
+
+ while(count > 0) {
+ size_t offset = pos & (PAGE_CACHE_SIZE - 1);
+ size_t write_bytes = min(count, PAGE_CACHE_SIZE - offset);
+ size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
+ PAGE_CACHE_SHIFT;
+
+ memset(pages, 0, sizeof(pages));
+ ret = prepare_pages(root, file, pages, num_pages,
+ pos, first_index, last_index,
+ write_bytes, alloc_extent_start);
+ BUG_ON(ret);
+
+ /* FIXME blocks != pagesize */
+ if (alloc_extent_start)
+ alloc_extent_start += num_pages;
+ ret = btrfs_copy_from_user(pos, num_pages,
+ write_bytes, pages, buf);
+ BUG_ON(ret);
+
+ ret = dirty_and_release_pages(NULL, root, file, pages,
+ num_pages, pos, write_bytes);
+ BUG_ON(ret);
+ btrfs_drop_pages(pages, num_pages);
+
+ buf += write_bytes;
+ count -= write_bytes;
+ pos += write_bytes;
+ num_written += write_bytes;
+
+ balance_dirty_pages_ratelimited(inode->i_mapping);
+ btrfs_btree_balance_dirty(root);
+ cond_resched();
+ }
+out_unlock:
+ mutex_unlock(&inode->i_mutex);
+out:
+ if (pinned[0])
+ page_cache_release(pinned[0]);
+ if (pinned[1])
+ page_cache_release(pinned[1]);
+ *ppos = pos;
+ current->backing_dev_info = NULL;
+ mark_inode_dirty(inode);
+ return num_written ? num_written : err;
+}
+
+/*
+ * FIXME, do this by stuffing the csum we want in the info hanging off
+ * page->private. For now, verify file csums on read
+ */
+static int btrfs_read_actor(read_descriptor_t *desc, struct page *page,
+ unsigned long offset, unsigned long size)
+{
+ char *kaddr;
+ unsigned long left, count = desc->count;
+ struct inode *inode = page->mapping->host;
+
+ if (size > count)
+ size = count;
+
+ if (!PageChecked(page)) {
+ /* FIXME, do it per block */
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ int ret;
+ struct buffer_head *bh;
+
+ if (page_has_buffers(page)) {
+ bh = page_buffers(page);
+ if (!buffer_mapped(bh)) {
+ SetPageChecked(page);
+ goto checked;
+ }
+ }
+
+ ret = btrfs_csum_verify_file_block(root,
+ page->mapping->host->i_ino,
+ page->index << PAGE_CACHE_SHIFT,
+ kmap(page), PAGE_CACHE_SIZE);
+ if (ret) {
+ if (ret != -ENOENT) {
+ printk("failed to verify ino %lu page %lu ret %d\n",
+ page->mapping->host->i_ino,
+ page->index, ret);
+ memset(page_address(page), 1, PAGE_CACHE_SIZE);
+ flush_dcache_page(page);
+ }
+ }
+ SetPageChecked(page);
+ kunmap(page);
+ }
+checked:
+ /*
+ * Faults on the destination of a read are common, so do it before
+ * taking the kmap.
+ */
+ if (!fault_in_pages_writeable(desc->arg.buf, size)) {
+ kaddr = kmap_atomic(page, KM_USER0);
+ left = __copy_to_user_inatomic(desc->arg.buf,
+ kaddr + offset, size);
+ kunmap_atomic(kaddr, KM_USER0);
+ if (left == 0)
+ goto success;
+ }
+
+ /* Do it the slow way */
+ kaddr = kmap(page);
+ left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
+ kunmap(page);
+
+ if (left) {
+ size -= left;
+ desc->error = -EFAULT;
+ }
+success:
+ desc->count = count - size;
+ desc->written += size;
+ desc->arg.buf += size;
+ return size;
+}
+
+/**
+ * btrfs_file_aio_read - filesystem read routine, with a mod to csum verify
+ * @iocb: kernel I/O control block
+ * @iov: io vector request
+ * @nr_segs: number of segments in the iovec
+ * @pos: current file position
+ */
+static ssize_t btrfs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
+ unsigned long nr_segs, loff_t pos)
+{
+ struct file *filp = iocb->ki_filp;
+ ssize_t retval;
+ unsigned long seg;
+ size_t count;
+ loff_t *ppos = &iocb->ki_pos;
+
+ count = 0;
+ for (seg = 0; seg < nr_segs; seg++) {
+ const struct iovec *iv = &iov[seg];
+
+ /*
+ * If any segment has a negative length, or the cumulative
+ * length ever wraps negative then return -EINVAL.
+ */
+ count += iv->iov_len;
+ if (unlikely((ssize_t)(count|iv->iov_len) < 0))
+ return -EINVAL;
+ if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
+ continue;
+ if (seg == 0)
+ return -EFAULT;
+ nr_segs = seg;
+ count -= iv->iov_len; /* This segment is no good */
+ break;
+ }
+ retval = 0;
+ if (count) {
+ for (seg = 0; seg < nr_segs; seg++) {
+ read_descriptor_t desc;
+
+ desc.written = 0;
+ desc.arg.buf = iov[seg].iov_base;
+ desc.count = iov[seg].iov_len;
+ if (desc.count == 0)
+ continue;
+ desc.error = 0;
+ do_generic_file_read(filp, ppos, &desc,
+ btrfs_read_actor);
+ retval += desc.written;
+ if (desc.error) {
+ retval = retval ?: desc.error;
+ break;
+ }
+ }
+ }
+ return retval;
+}
+
+static int btrfs_sync_file(struct file *file,
+ struct dentry *dentry, int datasync)
+{
+ struct inode *inode = dentry->d_inode;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ int ret;
+ struct btrfs_trans_handle *trans;
+
+ /*
+ * FIXME, use inode generation number to check if we can skip the
+ * commit
+ */
+ mutex_lock(&root->fs_info->fs_mutex);
+ trans = btrfs_start_transaction(root, 1);
+ if (!trans) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = btrfs_commit_transaction(trans, root);
+ mutex_unlock(&root->fs_info->fs_mutex);
+out:
+ return ret > 0 ? EIO : ret;
+}
+
+struct file_operations btrfs_file_operations = {
+ .llseek = generic_file_llseek,
+ .read = do_sync_read,
+ .aio_read = btrfs_file_aio_read,
+ .write = btrfs_file_write,
+ .mmap = generic_file_mmap,
+ .open = generic_file_open,
+ .ioctl = btrfs_ioctl,
+ .fsync = btrfs_sync_file,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = btrfs_compat_ioctl,
+#endif
+};
+