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linux/fs/btrfs/file.c
Sage Weil 6bf13c0cc8 Btrfs: transaction ioctls 
These ioctls let a user application hold a transaction open while it
performs a series of operations.  A final ioctl does a sync on the fs
(closing the current transaction).  This is the main requirement for
Ceph's OSD to be able to keep the data it's storing in a btrfs volume
consistent, and AFAICS it works just fine.  The application would do
something like

	fd = ::open("some/file", O_RDONLY);
	::ioctl(fd, BTRFS_IOC_TRANS_START);
	/* do a bunch of stuff */
	::ioctl(fd, BTRFS_IOC_TRANS_END);
or just
	::close(fd);

And to ensure it commits to disk,

	::ioctl(fd, BTRFS_IOC_SYNC);

When a transaction is held open, the trans_handle is attached to the
struct file (via private_data) so that it will get cleaned up if the
process dies unexpectedly.  A held transaction is also ended on fsync() to
avoid a deadlock.

A misbehaving application could also deliberately hold a transaction open,
effectively locking up the FS, so it may make sense to restrict something
like this to root or something.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-09-25 11:04:03 -04:00

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/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#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 <linux/version.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "ordered-data.h"
#include "ioctl.h"
#include "print-tree.h"
#include "compat.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 noinline insert_inline_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct inode *inode,
u64 offset, size_t size,
struct page **pages, size_t page_offset,
int num_pages)
{
struct btrfs_key key;
struct btrfs_path *path;
struct extent_buffer *leaf;
char *kaddr;
unsigned long ptr;
struct btrfs_file_extent_item *ei;
struct page *page;
u32 datasize;
int err = 0;
int ret;
int i;
ssize_t cur_size;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
btrfs_set_trans_block_group(trans, inode);
key.objectid = inode->i_ino;
key.offset = offset;
btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
if (ret < 0) {
err = ret;
goto fail;
}
if (ret == 1) {
struct btrfs_key found_key;
if (path->slots[0] == 0)
goto insert;
path->slots[0]--;
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (found_key.objectid != inode->i_ino)
goto insert;
if (found_key.type != BTRFS_EXTENT_DATA_KEY)
goto insert;
ei = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, ei) !=
BTRFS_FILE_EXTENT_INLINE) {
goto insert;
}
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
ret = 0;
}
if (ret == 0) {
u32 found_size;
u64 found_end;
leaf = path->nodes[0];
ei = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, ei) !=
BTRFS_FILE_EXTENT_INLINE) {
err = ret;
btrfs_print_leaf(root, leaf);
printk("found wasn't inline offset %Lu inode %lu\n",
offset, inode->i_ino);
goto fail;
}
found_size = btrfs_file_extent_inline_len(leaf,
btrfs_item_nr(leaf, path->slots[0]));
found_end = key.offset + found_size;
if (found_end < offset + size) {
btrfs_release_path(root, path);
ret = btrfs_search_slot(trans, root, &key, path,
offset + size - found_end, 1);
BUG_ON(ret != 0);
ret = btrfs_extend_item(trans, root, path,
offset + size - found_end);
if (ret) {
err = ret;
goto fail;
}
leaf = path->nodes[0];
ei = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
inode->i_blocks += (offset + size - found_end) >> 9;
}
if (found_end < offset) {
ptr = btrfs_file_extent_inline_start(ei) + found_size;
memset_extent_buffer(leaf, 0, ptr, offset - found_end);
}
} else {
insert:
btrfs_release_path(root, path);
datasize = offset + size - key.offset;
inode->i_blocks += datasize >> 9;
datasize = btrfs_file_extent_calc_inline_size(datasize);
ret = btrfs_insert_empty_item(trans, root, path, &key,
datasize);
if (ret) {
err = ret;
printk("got bad ret %d\n", ret);
goto fail;
}
leaf = path->nodes[0];
ei = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
btrfs_set_file_extent_generation(leaf, ei, trans->transid);
btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
}
ptr = btrfs_file_extent_inline_start(ei) + offset - key.offset;
cur_size = size;
i = 0;
while (size > 0) {
page = pages[i];
kaddr = kmap_atomic(page, KM_USER0);
cur_size = min_t(size_t, PAGE_CACHE_SIZE - page_offset, size);
write_extent_buffer(leaf, kaddr + page_offset, ptr, cur_size);
kunmap_atomic(kaddr, KM_USER0);
page_offset = 0;
ptr += cur_size;
size -= cur_size;
if (i >= num_pages) {
printk("i %d num_pages %d\n", i, num_pages);
}
i++;
}
btrfs_mark_buffer_dirty(leaf);
fail:
btrfs_free_path(path);
return err;
}
static int noinline 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 err = 0;
int i;
struct inode *inode = fdentry(file)->d_inode;
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
u64 hint_byte;
u64 num_bytes;
u64 start_pos;
u64 end_of_last_block;
u64 end_pos = pos + write_bytes;
u64 inline_size;
loff_t isize = i_size_read(inode);
start_pos = pos & ~((u64)root->sectorsize - 1);
num_bytes = (write_bytes + pos - start_pos +
root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
end_of_last_block = start_pos + num_bytes - 1;
lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
mutex_lock(&root->fs_info->fs_mutex);
trans = btrfs_start_transaction(root, 1);
if (!trans) {
err = -ENOMEM;
goto out_unlock;
}
btrfs_set_trans_block_group(trans, inode);
hint_byte = 0;
if ((end_of_last_block & 4095) == 0) {
printk("strange end of last %Lu %zu %Lu\n", start_pos, write_bytes, end_of_last_block);
}
set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
/* FIXME...EIEIO, ENOSPC and more */
/* insert any holes we need to create */
if (isize < end_pos) {
u64 last_pos_in_file;
u64 hole_size;
u64 mask = root->sectorsize - 1;
last_pos_in_file = (isize + mask) & ~mask;
hole_size = (end_pos - last_pos_in_file + mask) & ~mask;
if (last_pos_in_file < end_pos) {
err = btrfs_drop_extents(trans, root, inode,
last_pos_in_file,
last_pos_in_file + hole_size,
last_pos_in_file,
&hint_byte);
if (err)
goto failed;
err = btrfs_insert_file_extent(trans, root,
inode->i_ino,
last_pos_in_file,
0, 0, hole_size, 0);
btrfs_drop_extent_cache(inode, last_pos_in_file,
last_pos_in_file + hole_size -1);
btrfs_check_file(root, inode);
}
if (err)
goto failed;
}
/*
* either allocate an extent for the new bytes or setup the key
* to show we are doing inline data in the extent
*/
inline_size = end_pos;
if (isize >= BTRFS_MAX_INLINE_DATA_SIZE(root) ||
inline_size > root->fs_info->max_inline ||
(inline_size & (root->sectorsize -1)) == 0 ||
inline_size >= BTRFS_MAX_INLINE_DATA_SIZE(root)) {
u64 last_end;
for (i = 0; i < num_pages; i++) {
struct page *p = pages[i];
SetPageUptodate(p);
set_page_dirty(p);
}
last_end = (u64)(pages[num_pages -1]->index) <<
PAGE_CACHE_SHIFT;
last_end += PAGE_CACHE_SIZE - 1;
set_extent_delalloc(io_tree, start_pos, end_of_last_block,
GFP_NOFS);
btrfs_add_ordered_inode(inode);
} else {
u64 aligned_end;
/* step one, delete the existing extents in this range */
aligned_end = (pos + write_bytes + root->sectorsize - 1) &
~((u64)root->sectorsize - 1);
err = btrfs_drop_extents(trans, root, inode, start_pos,
aligned_end, aligned_end, &hint_byte);
if (err)
goto failed;
if (isize > inline_size)
inline_size = min_t(u64, isize, aligned_end);
inline_size -= start_pos;
err = insert_inline_extent(trans, root, inode, start_pos,
inline_size, pages, 0, num_pages);
btrfs_drop_extent_cache(inode, start_pos, aligned_end - 1);
BUG_ON(err);
}
if (end_pos > isize) {
i_size_write(inode, end_pos);
btrfs_update_inode(trans, root, inode);
}
failed:
err = btrfs_end_transaction(trans, root);
out_unlock:
mutex_unlock(&root->fs_info->fs_mutex);
unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
return err;
}
int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end)
{
struct extent_map *em;
struct extent_map *split = NULL;
struct extent_map *split2 = NULL;
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
u64 len = end - start + 1;
int ret;
int testend = 1;
if (end == (u64)-1) {
len = (u64)-1;
testend = 0;
}
while(1) {
if (!split)
split = alloc_extent_map(GFP_NOFS);
if (!split2)
split2 = alloc_extent_map(GFP_NOFS);
spin_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, start, len);
if (!em) {
spin_unlock(&em_tree->lock);
break;
}
remove_extent_mapping(em_tree, em);
if (em->block_start < EXTENT_MAP_LAST_BYTE &&
em->start < start) {
split->start = em->start;
split->len = start - em->start;
split->block_start = em->block_start;
split->bdev = em->bdev;
split->flags = em->flags;
ret = add_extent_mapping(em_tree, split);
BUG_ON(ret);
free_extent_map(split);
split = split2;
split2 = NULL;
}
if (em->block_start < EXTENT_MAP_LAST_BYTE &&
testend && em->start + em->len > start + len) {
u64 diff = start + len - em->start;
split->start = start + len;
split->len = em->start + em->len - (start + len);
split->bdev = em->bdev;
split->flags = em->flags;
split->block_start = em->block_start + diff;
ret = add_extent_mapping(em_tree, split);
BUG_ON(ret);
free_extent_map(split);
split = NULL;
}
spin_unlock(&em_tree->lock);
/* once for us */
free_extent_map(em);
/* once for the tree*/
free_extent_map(em);
}
if (split)
free_extent_map(split);
if (split2)
free_extent_map(split2);
return 0;
}
int btrfs_check_file(struct btrfs_root *root, struct inode *inode)
{
return 0;
#if 0
struct btrfs_path *path;
struct btrfs_key found_key;
struct extent_buffer *leaf;
struct btrfs_file_extent_item *extent;
u64 last_offset = 0;
int nritems;
int slot;
int found_type;
int ret;
int err = 0;
u64 extent_end = 0;
path = btrfs_alloc_path();
ret = btrfs_lookup_file_extent(NULL, root, path, inode->i_ino,
last_offset, 0);
while(1) {
nritems = btrfs_header_nritems(path->nodes[0]);
if (path->slots[0] >= nritems) {
ret = btrfs_next_leaf(root, path);
if (ret)
goto out;
nritems = btrfs_header_nritems(path->nodes[0]);
}
slot = path->slots[0];
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &found_key, slot);
if (found_key.objectid != inode->i_ino)
break;
if (found_key.type != BTRFS_EXTENT_DATA_KEY)
goto out;
if (found_key.offset < last_offset) {
WARN_ON(1);
btrfs_print_leaf(root, leaf);
printk("inode %lu found offset %Lu expected %Lu\n",
inode->i_ino, found_key.offset, last_offset);
err = 1;
goto out;
}
extent = btrfs_item_ptr(leaf, slot,
struct btrfs_file_extent_item);
found_type = btrfs_file_extent_type(leaf, extent);
if (found_type == BTRFS_FILE_EXTENT_REG) {
extent_end = found_key.offset +
btrfs_file_extent_num_bytes(leaf, extent);
} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
struct btrfs_item *item;
item = btrfs_item_nr(leaf, slot);
extent_end = found_key.offset +
btrfs_file_extent_inline_len(leaf, item);
extent_end = (extent_end + root->sectorsize - 1) &
~((u64)root->sectorsize -1 );
}
last_offset = extent_end;
path->slots[0]++;
}
if (0 && last_offset < inode->i_size) {
WARN_ON(1);
btrfs_print_leaf(root, leaf);
printk("inode %lu found offset %Lu size %Lu\n", inode->i_ino,
last_offset, inode->i_size);
err = 1;
}
out:
btrfs_free_path(path);
return err;
#endif
}
/*
* 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 inline_limit, u64 *hint_byte)
{
u64 extent_end = 0;
u64 search_start = start;
struct extent_buffer *leaf;
struct btrfs_file_extent_item *extent;
struct btrfs_path *path;
struct btrfs_key key;
struct btrfs_file_extent_item old;
int keep;
int slot;
int bookend;
int found_type;
int found_extent;
int found_inline;
int recow;
int ret;
btrfs_drop_extent_cache(inode, start, end - 1);
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
while(1) {
recow = 0;
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]--;
}
next_slot:
keep = 0;
bookend = 0;
found_extent = 0;
found_inline = 0;
extent = NULL;
leaf = path->nodes[0];
slot = path->slots[0];
ret = 0;
btrfs_item_key_to_cpu(leaf, &key, slot);
if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
key.offset >= end) {
goto out;
}
if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
key.objectid != inode->i_ino) {
goto out;
}
if (recow) {
search_start = key.offset;
continue;
}
if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
extent = btrfs_item_ptr(leaf, slot,
struct btrfs_file_extent_item);
found_type = btrfs_file_extent_type(leaf, extent);
if (found_type == BTRFS_FILE_EXTENT_REG) {
extent_end =
btrfs_file_extent_disk_bytenr(leaf,
extent);
if (extent_end)
*hint_byte = extent_end;
extent_end = key.offset +
btrfs_file_extent_num_bytes(leaf, extent);
found_extent = 1;
} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
struct btrfs_item *item;
item = btrfs_item_nr(leaf, slot);
found_inline = 1;
extent_end = key.offset +
btrfs_file_extent_inline_len(leaf, item);
}
} else {
extent_end = search_start;
}
/* we found nothing we can drop */
if ((!found_extent && !found_inline) ||
search_start >= extent_end) {
int nextret;
u32 nritems;
nritems = btrfs_header_nritems(leaf);
if (slot >= nritems - 1) {
nextret = btrfs_next_leaf(root, path);
if (nextret)
goto out;
recow = 1;
} else {
path->slots[0]++;
}
goto next_slot;
}
if (found_inline) {
u64 mask = root->sectorsize - 1;
search_start = (extent_end + mask) & ~mask;
} else
search_start = extent_end;
if (end <= extent_end && start >= key.offset && found_inline) {
*hint_byte = EXTENT_MAP_INLINE;
continue;
}
if (end < extent_end && end >= key.offset) {
if (found_extent) {
u64 disk_bytenr =
btrfs_file_extent_disk_bytenr(leaf, extent);
u64 disk_num_bytes =
btrfs_file_extent_disk_num_bytes(leaf,
extent);
read_extent_buffer(leaf, &old,
(unsigned long)extent,
sizeof(old));
if (disk_bytenr != 0) {
ret = btrfs_inc_extent_ref(trans, root,
disk_bytenr, disk_num_bytes,
root->root_key.objectid,
trans->transid,
key.objectid, end);
BUG_ON(ret);
}
}
bookend = 1;
if (found_inline && start <= key.offset)
keep = 1;
}
/* truncate existing extent */
if (start > key.offset) {
u64 new_num;
u64 old_num;
keep = 1;
WARN_ON(start & (root->sectorsize - 1));
if (found_extent) {
new_num = start - key.offset;
old_num = btrfs_file_extent_num_bytes(leaf,
extent);
*hint_byte =
btrfs_file_extent_disk_bytenr(leaf,
extent);
if (btrfs_file_extent_disk_bytenr(leaf,
extent)) {
dec_i_blocks(inode, old_num - new_num);
}
btrfs_set_file_extent_num_bytes(leaf, extent,
new_num);
btrfs_mark_buffer_dirty(leaf);
} else if (key.offset < inline_limit &&
(end > extent_end) &&
(inline_limit < extent_end)) {
u32 new_size;
new_size = btrfs_file_extent_calc_inline_size(
inline_limit - key.offset);
dec_i_blocks(inode, (extent_end - key.offset) -
(inline_limit - key.offset));
btrfs_truncate_item(trans, root, path,
new_size, 1);
}
}
/* delete the entire extent */
if (!keep) {
u64 disk_bytenr = 0;
u64 disk_num_bytes = 0;
u64 extent_num_bytes = 0;
u64 root_gen;
u64 root_owner;
root_gen = btrfs_header_generation(leaf);
root_owner = btrfs_header_owner(leaf);
if (found_extent) {
disk_bytenr =
btrfs_file_extent_disk_bytenr(leaf,
extent);
disk_num_bytes =
btrfs_file_extent_disk_num_bytes(leaf,
extent);
extent_num_bytes =
btrfs_file_extent_num_bytes(leaf, extent);
*hint_byte =
btrfs_file_extent_disk_bytenr(leaf,
extent);
}
ret = btrfs_del_item(trans, root, path);
/* TODO update progress marker and return */
BUG_ON(ret);
btrfs_release_path(root, path);
extent = NULL;
if (found_extent && disk_bytenr != 0) {
dec_i_blocks(inode, extent_num_bytes);
ret = btrfs_free_extent(trans, root,
disk_bytenr,
disk_num_bytes,
root_owner,
root_gen, inode->i_ino,
key.offset, 0);
}
BUG_ON(ret);
if (!bookend && search_start >= end) {
ret = 0;
goto out;
}
if (!bookend)
continue;
}
if (bookend && found_inline && start <= key.offset) {
u32 new_size;
new_size = btrfs_file_extent_calc_inline_size(
extent_end - end);
dec_i_blocks(inode, (extent_end - key.offset) -
(extent_end - end));
btrfs_truncate_item(trans, root, path, new_size, 0);
}
/* create bookend, splitting the extent in two */
if (bookend && found_extent) {
struct btrfs_key ins;
ins.objectid = inode->i_ino;
ins.offset = end;
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));
leaf = path->nodes[0];
if (ret) {
btrfs_print_leaf(root, leaf);
printk("got %d on inserting %Lu %u %Lu start %Lu end %Lu found %Lu %Lu keep was %d\n", ret , ins.objectid, ins.type, ins.offset, start, end, key.offset, extent_end, keep);
}
BUG_ON(ret);
extent = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
write_extent_buffer(leaf, &old,
(unsigned long)extent, sizeof(old));
btrfs_set_file_extent_offset(leaf, extent,
le64_to_cpu(old.offset) + end - key.offset);
WARN_ON(le64_to_cpu(old.num_bytes) <
(extent_end - end));
btrfs_set_file_extent_num_bytes(leaf, extent,
extent_end - end);
btrfs_set_file_extent_type(leaf, extent,
BTRFS_FILE_EXTENT_REG);
btrfs_mark_buffer_dirty(path->nodes[0]);
if (le64_to_cpu(old.disk_bytenr) != 0) {
inode->i_blocks +=
btrfs_file_extent_num_bytes(leaf,
extent) >> 9;
}
ret = 0;
goto out;
}
}
out:
btrfs_free_path(path);
btrfs_check_file(root, inode);
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)
{
int i;
unsigned long index = pos >> PAGE_CACHE_SHIFT;
struct inode *inode = fdentry(file)->d_inode;
int err = 0;
u64 start_pos;
start_pos = pos & ~((u64)root->sectorsize - 1);
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;
BUG_ON(1);
}
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
ClearPageDirty(pages[i]);
#else
cancel_dirty_page(pages[i], PAGE_CACHE_SIZE);
#endif
wait_on_page_writeback(pages[i]);
set_page_extent_mapped(pages[i]);
WARN_ON(!PageLocked(pages[i]));
}
if (start_pos < inode->i_size) {
u64 last_pos;
last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
lock_extent(&BTRFS_I(inode)->io_tree,
start_pos, last_pos - 1, GFP_NOFS);
clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
GFP_NOFS);
unlock_extent(&BTRFS_I(inode)->io_tree,
start_pos, last_pos - 1, GFP_NOFS);
}
return 0;
}
static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
loff_t pos;
loff_t start_pos;
ssize_t num_written = 0;
ssize_t err = 0;
int ret = 0;
struct inode *inode = fdentry(file)->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
struct page **pages = NULL;
int nrptrs;
struct page *pinned[2];
unsigned long first_index;
unsigned long last_index;
nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
PAGE_CACHE_SIZE / (sizeof(struct page *)));
pinned[0] = NULL;
pinned[1] = NULL;
pos = *ppos;
start_pos = pos;
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_nolock;
if (count == 0)
goto out_nolock;
#ifdef REMOVE_SUID_PATH
err = remove_suid(&file->f_path);
#else
err = remove_suid(fdentry(file));
#endif
if (err)
goto out_nolock;
file_update_time(file);
pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
mutex_lock(&inode->i_mutex);
first_index = pos >> PAGE_CACHE_SHIFT;
last_index = (pos + count) >> PAGE_CACHE_SHIFT;
/*
* if this is a nodatasum mount, force summing off for the inode
* all the time. That way a later mount with summing on won't
* get confused
*/
if (btrfs_test_opt(root, NODATASUM))
btrfs_set_flag(inode, NODATASUM);
/*
* 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 = btrfs_readpage(NULL, pinned[0]);
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 = btrfs_readpage(NULL, pinned[1]);
BUG_ON(ret);
wait_on_page_locked(pinned[1]);
} else {
unlock_page(pinned[1]);
}
}
while(count > 0) {
size_t offset = pos & (PAGE_CACHE_SIZE - 1);
size_t write_bytes = min(count, nrptrs *
(size_t)PAGE_CACHE_SIZE -
offset);
size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
PAGE_CACHE_SHIFT;
WARN_ON(num_pages > nrptrs);
memset(pages, 0, sizeof(pages));
mutex_lock(&root->fs_info->fs_mutex);
ret = btrfs_check_free_space(root, write_bytes, 0);
mutex_unlock(&root->fs_info->fs_mutex);
if (ret)
goto out;
ret = prepare_pages(root, file, pages, num_pages,
pos, first_index, last_index,
write_bytes);
if (ret)
goto out;
ret = btrfs_copy_from_user(pos, num_pages,
write_bytes, pages, buf);
if (ret) {
btrfs_drop_pages(pages, num_pages);
goto out;
}
ret = dirty_and_release_pages(NULL, root, file, pages,
num_pages, pos, write_bytes);
btrfs_drop_pages(pages, num_pages);
if (ret)
goto out;
buf += write_bytes;
count -= write_bytes;
pos += write_bytes;
num_written += write_bytes;
balance_dirty_pages_ratelimited_nr(inode->i_mapping, num_pages);
if (num_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
btrfs_btree_balance_dirty(root, 1);
btrfs_throttle(root);
cond_resched();
}
out:
mutex_unlock(&inode->i_mutex);
out_nolock:
kfree(pages);
if (pinned[0])
page_cache_release(pinned[0]);
if (pinned[1])
page_cache_release(pinned[1]);
*ppos = pos;
if (num_written > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
err = sync_page_range(inode, inode->i_mapping,
start_pos, num_written);
if (err < 0)
num_written = err;
} else if (num_written > 0 && (file->f_flags & O_DIRECT)) {
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
do_sync_file_range(file, start_pos,
start_pos + num_written - 1,
SYNC_FILE_RANGE_WRITE |
SYNC_FILE_RANGE_WAIT_AFTER);
#else
do_sync_mapping_range(inode->i_mapping, start_pos,
start_pos + num_written - 1,
SYNC_FILE_RANGE_WRITE |
SYNC_FILE_RANGE_WAIT_AFTER);
#endif
invalidate_mapping_pages(inode->i_mapping,
start_pos >> PAGE_CACHE_SHIFT,
(start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
}
current->backing_dev_info = NULL;
btrfs_ordered_throttle(root, inode);
return num_written ? num_written : err;
}
int btrfs_release_file(struct inode * inode, struct file * filp)
{
btrfs_del_ordered_inode(inode);
if (filp->private_data)
btrfs_ioctl_trans_end(filp);
return 0;
}
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 = 0;
struct btrfs_trans_handle *trans;
/*
* check the transaction that last modified this inode
* and see if its already been committed
*/
mutex_lock(&root->fs_info->fs_mutex);
if (!BTRFS_I(inode)->last_trans)
goto out;
mutex_lock(&root->fs_info->trans_mutex);
if (BTRFS_I(inode)->last_trans <=
root->fs_info->last_trans_committed) {
BTRFS_I(inode)->last_trans = 0;
mutex_unlock(&root->fs_info->trans_mutex);
goto out;
}
mutex_unlock(&root->fs_info->trans_mutex);
/*
* ok we haven't committed the transaction yet, lets do a commit
*/
if (file->private_data)
btrfs_ioctl_trans_end(file);
trans = btrfs_start_transaction(root, 1);
if (!trans) {
ret = -ENOMEM;
goto out;
}
ret = btrfs_commit_transaction(trans, root);
out:
mutex_unlock(&root->fs_info->fs_mutex);
return ret > 0 ? EIO : ret;
}
static struct vm_operations_struct btrfs_file_vm_ops = {
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
.nopage = filemap_nopage,
.populate = filemap_populate,
#else
.fault = filemap_fault,
#endif
.page_mkwrite = btrfs_page_mkwrite,
};
static int btrfs_file_mmap(struct file *filp, struct vm_area_struct *vma)
{
vma->vm_ops = &btrfs_file_vm_ops;
file_accessed(filp);
return 0;
}
struct file_operations btrfs_file_operations = {
.llseek = generic_file_llseek,
.read = do_sync_read,
.aio_read = generic_file_aio_read,
.splice_read = generic_file_splice_read,
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
.sendfile = generic_file_sendfile,
#endif
.write = btrfs_file_write,
.mmap = btrfs_file_mmap,
.open = generic_file_open,
.release = btrfs_release_file,
.fsync = btrfs_sync_file,
.unlocked_ioctl = btrfs_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = btrfs_ioctl,
#endif
};
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