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linux/fs/btrfs/file.c

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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 "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "ioctl.h"
#include "print-tree.h"
#include "tree-log.h"
#include "locking.h"
#include "compat.h"
/* simple helper to fault in pages and copy. This should go away
* and be replaced with calls into generic code.
*/
static noinline 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;
}
/*
* unlocks pages after btrfs_file_write is done with them
*/
static noinline 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;
/* page checked is some magic around finding pages that
* have been modified without going through btrfs_set_page_dirty
* clear it here
*/
ClearPageChecked(pages[i]);
unlock_page(pages[i]);
mark_page_accessed(pages[i]);
page_cache_release(pages[i]);
}
}
/*
* after copy_from_user, pages need to be dirtied and we need to make
* sure holes are created between the current EOF and the start of
* any next extents (if required).
*
* this also makes the decision about creating an inline extent vs
* doing real data extents, marking pages dirty and delalloc as required.
*/
static noinline 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 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;
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);
trans = btrfs_join_transaction(root, 1);
if (!trans) {
err = -ENOMEM;
goto out_unlock;
}
btrfs_set_trans_block_group(trans, inode);
hint_byte = 0;
set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
/* check for reserved extents on each page, we don't want
* to reset the delalloc bit on things that already have
* extents reserved.
*/
btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
for (i = 0; i < num_pages; i++) {
struct page *p = pages[i];
SetPageUptodate(p);
ClearPageChecked(p);
set_page_dirty(p);
}
if (end_pos > isize) {
i_size_write(inode, end_pos);
btrfs_update_inode(trans, root, inode);
}
err = btrfs_end_transaction(trans, root);
out_unlock:
unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
return err;
}
/*
* this drops all the extents in the cache that intersect the range
* [start, end]. Existing extents are split as required.
*/
int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
int skip_pinned)
{
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;
unsigned long flags;
int compressed = 0;
WARN_ON(end < start);
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;
}
flags = em->flags;
if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
spin_unlock(&em_tree->lock);
if (em->start <= start &&
(!testend || em->start + em->len >= start + len)) {
free_extent_map(em);
break;
}
if (start < em->start) {
len = em->start - start;
} else {
len = start + len - (em->start + em->len);
start = em->start + em->len;
}
free_extent_map(em);
continue;
}
compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
clear_bit(EXTENT_FLAG_PINNED, &em->flags);
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->orig_start = em->orig_start;
split->block_start = em->block_start;
if (compressed)
split->block_len = em->block_len;
else
split->block_len = split->len;
split->bdev = em->bdev;
split->flags = 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 = flags;
if (compressed) {
split->block_len = em->block_len;
split->block_start = em->block_start;
split->orig_start = em->orig_start;
} else {
split->block_len = split->len;
split->block_start = em->block_start + diff;
split->orig_start = split->start;
}
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(KERN_ERR "inode %lu found offset %llu "
"expected %llu\n", inode->i_ino,
(unsigned long long)found_key.offset,
(unsigned long long)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, extent);
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(KERN_ERR "inode %lu found offset %llu size %llu\n",
inode->i_ino, (unsigned long long)last_offset,
(unsigned long long)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.
*
* inline_limit is used to tell this code which offsets in the file to keep
* if they contain inline extents.
*/
noinline 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 locked_end = end;
u64 search_start = start;
u64 leaf_start;
u64 ram_bytes = 0;
u64 orig_parent = 0;
u64 disk_bytenr = 0;
u8 compression;
u8 encryption;
u16 other_encoding = 0;
u64 root_gen;
u64 root_owner;
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 = 0;
int found_extent;
int found_inline;
int recow;
int ret;
inline_limit = 0;
btrfs_drop_extent_cache(inode, start, end - 1, 0);
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;
leaf_start = 0;
root_gen = 0;
root_owner = 0;
compression = 0;
encryption = 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 = max(key.offset, start);
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);
compression = btrfs_file_extent_compression(leaf,
extent);
encryption = btrfs_file_extent_encryption(leaf,
extent);
other_encoding = btrfs_file_extent_other_encoding(leaf,
extent);
if (found_type == BTRFS_FILE_EXTENT_REG ||
found_type == BTRFS_FILE_EXTENT_PREALLOC) {
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);
ram_bytes = btrfs_file_extent_ram_bytes(leaf,
extent);
found_extent = 1;
} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
found_inline = 1;
extent_end = key.offset +
btrfs_file_extent_inline_len(leaf, extent);
}
} 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 (end <= extent_end && start >= key.offset && found_inline)
*hint_byte = EXTENT_MAP_INLINE;
if (found_extent) {
read_extent_buffer(leaf, &old, (unsigned long)extent,
sizeof(old));
root_gen = btrfs_header_generation(leaf);
root_owner = btrfs_header_owner(leaf);
leaf_start = leaf->start;
}
if (end < extent_end && end >= key.offset) {
bookend = 1;
if (found_inline && start <= key.offset)
keep = 1;
}
if (bookend && found_extent) {
if (locked_end < extent_end) {
ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
locked_end, extent_end - 1,
GFP_NOFS);
if (!ret) {
btrfs_release_path(root, path);
lock_extent(&BTRFS_I(inode)->io_tree,
locked_end, extent_end - 1,
GFP_NOFS);
locked_end = extent_end;
continue;
}
locked_end = extent_end;
}
orig_parent = path->nodes[0]->start;
disk_bytenr = le64_to_cpu(old.disk_bytenr);
if (disk_bytenr != 0) {
ret = btrfs_inc_extent_ref(trans, root,
disk_bytenr,
le64_to_cpu(old.disk_num_bytes),
orig_parent, root->root_key.objectid,
trans->transid, inode->i_ino);
BUG_ON(ret);
}
}
if (found_inline) {
u64 mask = root->sectorsize - 1;
search_start = (extent_end + mask) & ~mask;
} else
search_start = extent_end;
/* 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)) {
inode_sub_bytes(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);
inode_sub_bytes(inode, extent_end -
inline_limit);
btrfs_set_file_extent_ram_bytes(leaf, extent,
new_size);
if (!compression && !encryption) {
btrfs_truncate_item(trans, root, path,
new_size, 1);
}
}
}
/* delete the entire extent */
if (!keep) {
if (found_inline)
inode_sub_bytes(inode, extent_end -
key.offset);
ret = btrfs_del_item(trans, root, path);
/* TODO update progress marker and return */
BUG_ON(ret);
extent = NULL;
btrfs_release_path(root, path);
/* the extent will be freed later */
}
if (bookend && found_inline && start <= key.offset) {
u32 new_size;
new_size = btrfs_file_extent_calc_inline_size(
extent_end - end);
inode_sub_bytes(inode, end - key.offset);
btrfs_set_file_extent_ram_bytes(leaf, extent,
new_size);
if (!compression && !encryption)
ret = btrfs_truncate_item(trans, root, path,
new_size, 0);
BUG_ON(ret);
}
/* 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));
BUG_ON(ret);
leaf = path->nodes[0];
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_compression(leaf, extent,
compression);
btrfs_set_file_extent_encryption(leaf, extent,
encryption);
btrfs_set_file_extent_other_encoding(leaf, extent,
other_encoding);
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);
/*
* set the ram bytes to the size of the full extent
* before splitting. This is a worst case flag,
* but its the best we can do because we don't know
* how splitting affects compression
*/
btrfs_set_file_extent_ram_bytes(leaf, extent,
ram_bytes);
btrfs_set_file_extent_type(leaf, extent, found_type);
btrfs_mark_buffer_dirty(path->nodes[0]);
if (disk_bytenr != 0) {
ret = btrfs_update_extent_ref(trans, root,
disk_bytenr, orig_parent,
leaf->start,
root->root_key.objectid,
trans->transid, ins.objectid);
BUG_ON(ret);
}
btrfs_release_path(root, path);
if (disk_bytenr != 0)
inode_add_bytes(inode, extent_end - end);
}
if (found_extent && !keep) {
u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
if (old_disk_bytenr != 0) {
inode_sub_bytes(inode,
le64_to_cpu(old.num_bytes));
ret = btrfs_free_extent(trans, root,
old_disk_bytenr,
le64_to_cpu(old.disk_num_bytes),
leaf_start, root_owner,
root_gen, key.objectid, 0);
BUG_ON(ret);
*hint_byte = old_disk_bytenr;
}
}
if (search_start >= end) {
ret = 0;
goto out;
}
}
out:
btrfs_free_path(path);
if (locked_end > end) {
unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
GFP_NOFS);
}
btrfs_check_file(root, inode);
return ret;
}
static int extent_mergeable(struct extent_buffer *leaf, int slot,
u64 objectid, u64 bytenr, u64 *start, u64 *end)
{
struct btrfs_file_extent_item *fi;
struct btrfs_key key;
u64 extent_end;
if (slot < 0 || slot >= btrfs_header_nritems(leaf))
return 0;
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
return 0;
fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
btrfs_file_extent_compression(leaf, fi) ||
btrfs_file_extent_encryption(leaf, fi) ||
btrfs_file_extent_other_encoding(leaf, fi))
return 0;
extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
if ((*start && *start != key.offset) || (*end && *end != extent_end))
return 0;
*start = key.offset;
*end = extent_end;
return 1;
}
/*
* Mark extent in the range start - end as written.
*
* This changes extent type from 'pre-allocated' to 'regular'. If only
* part of extent is marked as written, the extent will be split into
* two or three.
*/
int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct inode *inode, u64 start, u64 end)
{
struct extent_buffer *leaf;
struct btrfs_path *path;
struct btrfs_file_extent_item *fi;
struct btrfs_key key;
u64 bytenr;
u64 num_bytes;
u64 extent_end;
u64 extent_offset;
u64 other_start;
u64 other_end;
u64 split = start;
u64 locked_end = end;
u64 orig_parent;
int extent_type;
int split_end = 1;
int ret;
btrfs_drop_extent_cache(inode, start, end - 1, 0);
path = btrfs_alloc_path();
BUG_ON(!path);
again:
key.objectid = inode->i_ino;
key.type = BTRFS_EXTENT_DATA_KEY;
if (split == start)
key.offset = split;
else
key.offset = split - 1;
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret > 0 && path->slots[0] > 0)
path->slots[0]--;
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
BUG_ON(key.objectid != inode->i_ino ||
key.type != BTRFS_EXTENT_DATA_KEY);
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
extent_type = btrfs_file_extent_type(leaf, fi);
BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
BUG_ON(key.offset > start || extent_end < end);
bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
extent_offset = btrfs_file_extent_offset(leaf, fi);
if (key.offset == start)
split = end;
if (key.offset == start && extent_end == end) {
int del_nr = 0;
int del_slot = 0;
u64 leaf_owner = btrfs_header_owner(leaf);
u64 leaf_gen = btrfs_header_generation(leaf);
other_start = end;
other_end = 0;
if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
bytenr, &other_start, &other_end)) {
extent_end = other_end;
del_slot = path->slots[0] + 1;
del_nr++;
ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
leaf->start, leaf_owner,
leaf_gen, inode->i_ino, 0);
BUG_ON(ret);
}
other_start = 0;
other_end = start;
if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
bytenr, &other_start, &other_end)) {
key.offset = other_start;
del_slot = path->slots[0];
del_nr++;
ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
leaf->start, leaf_owner,
leaf_gen, inode->i_ino, 0);
BUG_ON(ret);
}
split_end = 0;
if (del_nr == 0) {
btrfs_set_file_extent_type(leaf, fi,
BTRFS_FILE_EXTENT_REG);
goto done;
}
fi = btrfs_item_ptr(leaf, del_slot - 1,
struct btrfs_file_extent_item);
btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
btrfs_set_file_extent_num_bytes(leaf, fi,
extent_end - key.offset);
btrfs_mark_buffer_dirty(leaf);
ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
BUG_ON(ret);
goto done;
} else if (split == start) {
if (locked_end < extent_end) {
ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
locked_end, extent_end - 1, GFP_NOFS);
if (!ret) {
btrfs_release_path(root, path);
lock_extent(&BTRFS_I(inode)->io_tree,
locked_end, extent_end - 1, GFP_NOFS);
locked_end = extent_end;
goto again;
}
locked_end = extent_end;
}
btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
extent_offset += split - key.offset;
} else {
BUG_ON(key.offset != start);
btrfs_set_file_extent_offset(leaf, fi, extent_offset +
split - key.offset);
btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
key.offset = split;
btrfs_set_item_key_safe(trans, root, path, &key);
extent_end = split;
}
if (extent_end == end) {
split_end = 0;
extent_type = BTRFS_FILE_EXTENT_REG;
}
if (extent_end == end && split == start) {
other_start = end;
other_end = 0;
if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
bytenr, &other_start, &other_end)) {
path->slots[0]++;
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
key.offset = split;
btrfs_set_item_key_safe(trans, root, path, &key);
btrfs_set_file_extent_offset(leaf, fi, extent_offset);
btrfs_set_file_extent_num_bytes(leaf, fi,
other_end - split);
goto done;
}
}
if (extent_end == end && split == end) {
other_start = 0;
other_end = start;
if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
bytenr, &other_start, &other_end)) {
path->slots[0]--;
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
other_start);
goto done;
}
}
btrfs_mark_buffer_dirty(leaf);
orig_parent = leaf->start;
ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
orig_parent, root->root_key.objectid,
trans->transid, inode->i_ino);
BUG_ON(ret);
btrfs_release_path(root, path);
key.offset = start;
ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
BUG_ON(ret);
leaf = path->nodes[0];
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
btrfs_set_file_extent_generation(leaf, fi, trans->transid);
btrfs_set_file_extent_type(leaf, fi, extent_type);
btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
btrfs_set_file_extent_offset(leaf, fi, extent_offset);
btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
btrfs_set_file_extent_compression(leaf, fi, 0);
btrfs_set_file_extent_encryption(leaf, fi, 0);
btrfs_set_file_extent_other_encoding(leaf, fi, 0);
if (orig_parent != leaf->start) {
ret = btrfs_update_extent_ref(trans, root, bytenr,
orig_parent, leaf->start,
root->root_key.objectid,
trans->transid, inode->i_ino);
BUG_ON(ret);
}
done:
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(root, path);
if (split_end && split == start) {
split = end;
goto again;
}
if (locked_end > end) {
unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
GFP_NOFS);
}
btrfs_free_path(path);
return 0;
}
/*
* this gets pages into the page cache and locks them down, it also properly
* waits for data=ordered extents to finish before allowing the pages to be
* modified.
*/
static noinline 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;
u64 last_pos;
start_pos = pos & ~((u64)root->sectorsize - 1);
last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
if (start_pos > inode->i_size) {
err = btrfs_cont_expand(inode, start_pos);
if (err)
return err;
}
memset(pages, 0, num_pages * sizeof(struct page *));
again:
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);
}
wait_on_page_writeback(pages[i]);
}
if (start_pos < inode->i_size) {
struct btrfs_ordered_extent *ordered;
lock_extent(&BTRFS_I(inode)->io_tree,
start_pos, last_pos - 1, GFP_NOFS);
ordered = btrfs_lookup_first_ordered_extent(inode,
last_pos - 1);
if (ordered &&
ordered->file_offset + ordered->len > start_pos &&
ordered->file_offset < last_pos) {
btrfs_put_ordered_extent(ordered);
unlock_extent(&BTRFS_I(inode)->io_tree,
start_pos, last_pos - 1, GFP_NOFS);
for (i = 0; i < num_pages; i++) {
unlock_page(pages[i]);
page_cache_release(pages[i]);
}
btrfs_wait_ordered_range(inode, start_pos,
last_pos - start_pos);
goto again;
}
if (ordered)
btrfs_put_ordered_extent(ordered);
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);
}
for (i = 0; i < num_pages; i++) {
clear_page_dirty_for_io(pages[i]);
set_page_extent_mapped(pages[i]);
WARN_ON(!PageLocked(pages[i]));
}
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;
int will_write;
will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
(file->f_flags & O_DIRECT));
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;
err = file_remove_suid(file);
if (err)
goto out_nolock;
file_update_time(file);
pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
mutex_lock(&inode->i_mutex);
BTRFS_I(inode)->sequence++;
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 = 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(struct page *) * nrptrs);
ret = btrfs_check_data_free_space(root, inode, write_bytes);
if (ret)
goto out;
ret = prepare_pages(root, file, pages, num_pages,
pos, first_index, last_index,
write_bytes);
if (ret) {
btrfs_free_reserved_data_space(root, inode,
write_bytes);
goto out;
}
ret = btrfs_copy_from_user(pos, num_pages,
write_bytes, pages, buf);
if (ret) {
btrfs_free_reserved_data_space(root, inode,
write_bytes);
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) {
btrfs_free_reserved_data_space(root, inode,
write_bytes);
goto out;
}
if (will_write) {
btrfs_fdatawrite_range(inode->i_mapping, pos,
pos + write_bytes - 1,
WB_SYNC_NONE);
} else {
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);
}
buf += write_bytes;
count -= write_bytes;
pos += write_bytes;
num_written += write_bytes;
cond_resched();
}
out:
mutex_unlock(&inode->i_mutex);
if (ret)
err = ret;
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 && will_write) {
struct btrfs_trans_handle *trans;
err = btrfs_wait_ordered_range(inode, start_pos, num_written);
if (err)
num_written = err;
if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
trans = btrfs_start_transaction(root, 1);
ret = btrfs_log_dentry_safe(trans, root,
file->f_dentry);
if (ret == 0) {
btrfs_sync_log(trans, root);
btrfs_end_transaction(trans, root);
} else {
btrfs_commit_transaction(trans, root);
}
}
if (file->f_flags & O_DIRECT) {
invalidate_mapping_pages(inode->i_mapping,
start_pos >> PAGE_CACHE_SHIFT,
(start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
}
}
current->backing_dev_info = NULL;
return num_written ? num_written : err;
}
int btrfs_release_file(struct inode *inode, struct file *filp)
{
if (filp->private_data)
btrfs_ioctl_trans_end(filp);
return 0;
}
/*
* fsync call for both files and directories. This logs the inode into
* the tree log instead of forcing full commits whenever possible.
*
* It needs to call filemap_fdatawait so that all ordered extent updates are
* in the metadata btree are up to date for copying to the log.
*
* It drops the inode mutex before doing the tree log commit. This is an
* important optimization for directories because holding the mutex prevents
* new operations on the dir while we write to disk.
*/
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
*/
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);
root->log_batch++;
filemap_fdatawrite(inode->i_mapping);
btrfs_wait_ordered_range(inode, 0, (u64)-1);
root->log_batch++;
/*
* ok we haven't committed the transaction yet, lets do a commit
*/
if (file && file->private_data)
btrfs_ioctl_trans_end(file);
trans = btrfs_start_transaction(root, 1);
if (!trans) {
ret = -ENOMEM;
goto out;
}
ret = btrfs_log_dentry_safe(trans, root, dentry);
if (ret < 0)
goto out;
/* we've logged all the items and now have a consistent
* version of the file in the log. It is possible that
* someone will come in and modify the file, but that's
* fine because the log is consistent on disk, and we
* have references to all of the file's extents
*
* It is possible that someone will come in and log the
* file again, but that will end up using the synchronization
* inside btrfs_sync_log to keep things safe.
*/
mutex_unlock(&dentry->d_inode->i_mutex);
if (ret > 0) {
ret = btrfs_commit_transaction(trans, root);
} else {
btrfs_sync_log(trans, root);
ret = btrfs_end_transaction(trans, root);
}
mutex_lock(&dentry->d_inode->i_mutex);
out:
return ret > 0 ? EIO : ret;
}
static struct vm_operations_struct btrfs_file_vm_ops = {
.fault = filemap_fault,
.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,
.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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