提交 75dfe396 编写于 作者: C Chris Mason 提交者: David Woodhouse

btrfs_file_write -- first pass

Signed-off-by: NChris Mason <chris.mason@oracle.com>
上级 30ae8467
......@@ -9,6 +9,8 @@
#include <linux/smp_lock.h>
#include <linux/backing-dev.h>
#include <linux/mpage.h>
#include <linux/swap.h>
#include <linux/writeback.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
......@@ -755,7 +757,7 @@ printk("btrfs sync_fs\n");
return 0;
}
static int btrfs_get_block(struct inode *inode, sector_t iblock,
static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
struct buffer_head *result, int create)
{
int ret;
......@@ -772,7 +774,6 @@ static int btrfs_get_block(struct inode *inode, sector_t iblock,
struct btrfs_disk_key *found_key;
btrfs_init_path(&path);
mutex_lock(&root->fs_info->fs_mutex);
if (create)
trans = btrfs_start_transaction(root, 1);
......@@ -848,6 +849,16 @@ static int btrfs_get_block(struct inode *inode, sector_t iblock,
out:
if (trans)
btrfs_end_transaction(trans, root);
return err;
}
static int btrfs_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *result, int create)
{
int err;
struct btrfs_root *root = btrfs_sb(inode->i_sb);
mutex_lock(&root->fs_info->fs_mutex);
err = btrfs_get_block_lock(inode, iblock, result, create);
mutex_unlock(&root->fs_info->fs_mutex);
return err;
}
......@@ -855,8 +866,15 @@ static int btrfs_get_block(struct inode *inode, sector_t iblock,
static int btrfs_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
WARN_ON(1);
return nobh_prepare_write(page, from, to, btrfs_get_block);
}
static int btrfs_commit_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
WARN_ON(1);
return nobh_commit_write(file, page, from, to);
}
static void btrfs_write_super(struct super_block *sb)
{
......@@ -903,6 +921,196 @@ static void btrfs_truncate(struct inode *inode)
mark_inode_dirty(inode);
}
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;
for (i = 0; i < num_pages; i++) {
offset = pos & (PAGE_CACHE_SIZE -1);
this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
ret = nobh_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;
}
static int prepare_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;
unsigned long index = pos >> PAGE_CACHE_SHIFT;
struct inode *inode = file->f_path.dentry->d_inode;
int offset;
int err = 0;
int ret;
int this_write;
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;
}
offset = pos & (PAGE_CACHE_SIZE -1);
this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
ret = nobh_prepare_write(pages[i], offset,
offset + this_write,
btrfs_get_block_lock);
pos += this_write;
if (ret) {
err = ret;
goto failed_truncate;
}
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 btrfs_trans_handle *trans;
struct inode *inode = file->f_path.dentry->d_inode;
struct btrfs_root *root = btrfs_sb(inode->i_sb);
struct page *pages[1];
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);
mutex_lock(&inode->i_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;
mutex_lock(&root->fs_info->fs_mutex);
trans = btrfs_start_transaction(root, 1);
ret = prepare_pages(trans, root, file, pages, num_pages,
pos, write_bytes);
BUG_ON(ret);
ret = btrfs_copy_from_user(pos, num_pages,
write_bytes, pages, buf);
BUG_ON(ret);
mutex_unlock(&root->fs_info->fs_mutex);
ret = dirty_and_release_pages(trans, root, file, pages,
num_pages, pos, write_bytes);
BUG_ON(ret);
btrfs_drop_pages(pages, num_pages);
ret = btrfs_end_transaction(trans, root);
buf += write_bytes;
count -= write_bytes;
pos += write_bytes;
num_written += write_bytes;
balance_dirty_pages_ratelimited(inode->i_mapping);
cond_resched();
}
mutex_unlock(&inode->i_mutex);
out:
*ppos = pos;
current->backing_dev_info = NULL;
return num_written ? num_written : err;
}
static int btrfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
......@@ -948,7 +1156,7 @@ static struct address_space_operations btrfs_aops = {
.writepage = btrfs_writepage,
.sync_page = block_sync_page,
.prepare_write = btrfs_prepare_write,
.commit_write = nobh_commit_write,
.commit_write = btrfs_commit_write,
};
static struct inode_operations btrfs_file_inode_operations = {
......@@ -958,14 +1166,10 @@ static struct inode_operations btrfs_file_inode_operations = {
static struct file_operations btrfs_file_operations = {
.llseek = generic_file_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = generic_file_aio_read,
.aio_write = generic_file_aio_write,
.aio_read = generic_file_aio_read,
.write = btrfs_file_write,
.mmap = generic_file_mmap,
.open = generic_file_open,
.sendfile = generic_file_sendfile,
.splice_read = generic_file_splice_read,
.splice_write = generic_file_splice_write,
};
static int __init init_btrfs_fs(void)
......
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