/**
* aops.c - NTFS kernel address space operations and page cache handling.
* Part of the Linux-NTFS project.
*
* Copyright (c) 2001-2005 Anton Altaparmakov
* Copyright (c) 2002 Richard Russon
*
* This program/include file is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program/include file 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 (in the main directory of the Linux-NTFS
* distribution in the file COPYING); if not, write to the Free Software
* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include "aops.h"
#include "attrib.h"
#include "debug.h"
#include "inode.h"
#include "mft.h"
#include "runlist.h"
#include "types.h"
#include "ntfs.h"
/**
* ntfs_end_buffer_async_read - async io completion for reading attributes
* @bh: buffer head on which io is completed
* @uptodate: whether @bh is now uptodate or not
*
* Asynchronous I/O completion handler for reading pages belonging to the
* attribute address space of an inode. The inodes can either be files or
* directories or they can be fake inodes describing some attribute.
*
* If NInoMstProtected(), perform the post read mst fixups when all IO on the
* page has been completed and mark the page uptodate or set the error bit on
* the page. To determine the size of the records that need fixing up, we
* cheat a little bit by setting the index_block_size in ntfs_inode to the ntfs
* record size, and index_block_size_bits, to the log(base 2) of the ntfs
* record size.
*/
static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
{
static DEFINE_SPINLOCK(page_uptodate_lock);
unsigned long flags;
struct buffer_head *tmp;
struct page *page;
ntfs_inode *ni;
int page_uptodate = 1;
page = bh->b_page;
ni = NTFS_I(page->mapping->host);
if (likely(uptodate)) {
s64 file_ofs, initialized_size;
set_buffer_uptodate(bh);
file_ofs = ((s64)page->index << PAGE_CACHE_SHIFT) +
bh_offset(bh);
read_lock_irqsave(&ni->size_lock, flags);
initialized_size = ni->initialized_size;
read_unlock_irqrestore(&ni->size_lock, flags);
/* Check for the current buffer head overflowing. */
if (file_ofs + bh->b_size > initialized_size) {
char *addr;
int ofs = 0;
if (file_ofs < initialized_size)
ofs = initialized_size - file_ofs;
addr = kmap_atomic(page, KM_BIO_SRC_IRQ);
memset(addr + bh_offset(bh) + ofs, 0, bh->b_size - ofs);
flush_dcache_page(page);
kunmap_atomic(addr, KM_BIO_SRC_IRQ);
}
} else {
clear_buffer_uptodate(bh);
ntfs_error(ni->vol->sb, "Buffer I/O error, logical block %llu.",
(unsigned long long)bh->b_blocknr);
SetPageError(page);
}
spin_lock_irqsave(&page_uptodate_lock, flags);
clear_buffer_async_read(bh);
unlock_buffer(bh);
tmp = bh;
do {
if (!buffer_uptodate(tmp))
page_uptodate = 0;
if (buffer_async_read(tmp)) {
if (likely(buffer_locked(tmp)))
goto still_busy;
/* Async buffers must be locked. */
BUG();
}
tmp = tmp->b_this_page;
} while (tmp != bh);
spin_unlock_irqrestore(&page_uptodate_lock, flags);
/*
* If none of the buffers had errors then we can set the page uptodate,
* but we first have to perform the post read mst fixups, if the
* attribute is mst protected, i.e. if NInoMstProteced(ni) is true.
* Note we ignore fixup errors as those are detected when
* map_mft_record() is called which gives us per record granularity
* rather than per page granularity.
*/
if (!NInoMstProtected(ni)) {
if (likely(page_uptodate && !PageError(page)))
SetPageUptodate(page);
} else {
char *addr;
unsigned int i, recs;
u32 rec_size;
rec_size = ni->itype.index.block_size;
recs = PAGE_CACHE_SIZE / rec_size;
/* Should have been verified before we got here... */
BUG_ON(!recs);
addr = kmap_atomic(page, KM_BIO_SRC_IRQ);
for (i = 0; i < recs; i++)
post_read_mst_fixup((NTFS_RECORD*)(addr +
i * rec_size), rec_size);
flush_dcache_page(page);
kunmap_atomic(addr, KM_BIO_SRC_IRQ);
if (likely(page_uptodate && !PageError(page)))
SetPageUptodate(page);
}
unlock_page(page);
return;
still_busy:
spin_unlock_irqrestore(&page_uptodate_lock, flags);
return;
}
/**
* ntfs_read_block - fill a @page of an address space with data
* @page: page cache page to fill with data
*
* Fill the page @page of the address space belonging to the @page->host inode.
* We read each buffer asynchronously and when all buffers are read in, our io
* completion handler ntfs_end_buffer_read_async(), if required, automatically
* applies the mst fixups to the page before finally marking it uptodate and
* unlocking it.
*
* We only enforce allocated_size limit because i_size is checked for in
* generic_file_read().
*
* Return 0 on success and -errno on error.
*
* Contains an adapted version of fs/buffer.c::block_read_full_page().
*/
static int ntfs_read_block(struct page *page)
{
VCN vcn;
LCN lcn;
ntfs_inode *ni;
ntfs_volume *vol;
runlist_element *rl;
struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
sector_t iblock, lblock, zblock;
unsigned long flags;
unsigned int blocksize, vcn_ofs;
int i, nr;
unsigned char blocksize_bits;
ni = NTFS_I(page->mapping->host);
vol = ni->vol;
/* $MFT/$DATA must have its complete runlist in memory at all times. */
BUG_ON(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni));
blocksize_bits = VFS_I(ni)->i_blkbits;
blocksize = 1 << blocksize_bits;
if (!page_has_buffers(page))
create_empty_buffers(page, blocksize, 0);
bh = head = page_buffers(page);
if (unlikely(!bh)) {
unlock_page(page);
return -ENOMEM;
}
iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
read_lock_irqsave(&ni->size_lock, flags);
lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits;
zblock = (ni->initialized_size + blocksize - 1) >> blocksize_bits;
read_unlock_irqrestore(&ni->size_lock, flags);
/* Loop through all the buffers in the page. */
rl = NULL;
nr = i = 0;
do {
u8 *kaddr;
if (unlikely(buffer_uptodate(bh)))
continue;
if (unlikely(buffer_mapped(bh))) {
arr[nr++] = bh;
continue;
}
bh->b_bdev = vol->sb->s_bdev;
/* Is the block within the allowed limits? */
if (iblock < lblock) {
BOOL is_retry = FALSE;
/* Convert iblock into corresponding vcn and offset. */
vcn = (VCN)iblock << blocksize_bits >>
vol->cluster_size_bits;
vcn_ofs = ((VCN)iblock << blocksize_bits) &
vol->cluster_size_mask;
if (!rl) {
lock_retry_remap:
down_read(&ni->runlist.lock);
rl = ni->runlist.rl;
}
if (likely(rl != NULL)) {
/* Seek to element containing target vcn. */
while (rl->length && rl[1].vcn <= vcn)
rl++;
lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
} else
lcn = LCN_RL_NOT_MAPPED;
/* Successful remap. */
if (lcn >= 0) {
/* Setup buffer head to correct block. */
bh->b_blocknr = ((lcn << vol->cluster_size_bits)
+ vcn_ofs) >> blocksize_bits;
set_buffer_mapped(bh);
/* Only read initialized data blocks. */
if (iblock < zblock) {
arr[nr++] = bh;
continue;
}
/* Fully non-initialized data block, zero it. */
goto handle_zblock;
}
/* It is a hole, need to zero it. */
if (lcn == LCN_HOLE)
goto handle_hole;
/* If first try and runlist unmapped, map and retry. */
if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
int err;
is_retry = TRUE;
/*
* Attempt to map runlist, dropping lock for
* the duration.
*/
up_read(&ni->runlist.lock);
err = ntfs_map_runlist(ni, vcn);
if (likely(!err))
goto lock_retry_remap;
rl = NULL;
lcn = err;
}
/* Hard error, zero out region. */
bh->b_blocknr = -1;
SetPageError(page);
ntfs_error(vol->sb, "Failed to read from inode 0x%lx, "
"attribute type 0x%x, vcn 0x%llx, "
"offset 0x%x because its location on "
"disk could not be determined%s "
"(error code %lli).", ni->mft_no,
ni->type, (unsigned long long)vcn,
vcn_ofs, is_retry ? " even after "
"retrying" : "", (long long)lcn);
}
/*
* Either iblock was outside lblock limits or
* ntfs_rl_vcn_to_lcn() returned error. Just zero that portion
* of the page and set the buffer uptodate.
*/
handle_hole:
bh->b_blocknr = -1UL;
clear_buffer_mapped(bh);
handle_zblock:
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + i * blocksize, 0, blocksize);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
set_buffer_uptodate(bh);
} while (i++, iblock++, (bh = bh->b_this_page) != head);
/* Release the lock if we took it. */
if (rl)
up_read(&ni->runlist.lock);
/* Check we have at least one buffer ready for i/o. */
if (nr) {
struct buffer_head *tbh;
/* Lock the buffers. */
for (i = 0; i < nr; i++) {
tbh = arr[i];
lock_buffer(tbh);
tbh->b_end_io = ntfs_end_buffer_async_read;
set_buffer_async_read(tbh);
}
/* Finally, start i/o on the buffers. */
for (i = 0; i < nr; i++) {
tbh = arr[i];
if (likely(!buffer_uptodate(tbh)))
submit_bh(READ, tbh);
else
ntfs_end_buffer_async_read(tbh, 1);
}
return 0;
}
/* No i/o was scheduled on any of the buffers. */
if (likely(!PageError(page)))
SetPageUptodate(page);
else /* Signal synchronous i/o error. */
nr = -EIO;
unlock_page(page);
return nr;
}
/**
* ntfs_readpage - fill a @page of a @file with data from the device
* @file: open file to which the page @page belongs or NULL
* @page: page cache page to fill with data
*
* For non-resident attributes, ntfs_readpage() fills the @page of the open
* file @file by calling the ntfs version of the generic block_read_full_page()
* function, ntfs_read_block(), which in turn creates and reads in the buffers
* associated with the page asynchronously.
*
* For resident attributes, OTOH, ntfs_readpage() fills @page by copying the
* data from the mft record (which at this stage is most likely in memory) and
* fills the remainder with zeroes. Thus, in this case, I/O is synchronous, as
* even if the mft record is not cached at this point in time, we need to wait
* for it to be read in before we can do the copy.
*
* Return 0 on success and -errno on error.
*/
static int ntfs_readpage(struct file *file, struct page *page)
{
ntfs_inode *ni, *base_ni;
u8 *kaddr;
ntfs_attr_search_ctx *ctx;
MFT_RECORD *mrec;
unsigned long flags;
u32 attr_len;
int err = 0;
BUG_ON(!PageLocked(page));
/*
* This can potentially happen because we clear PageUptodate() during
* ntfs_writepage() of MstProtected() attributes.
*/
if (PageUptodate(page)) {
unlock_page(page);
return 0;
}
ni = NTFS_I(page->mapping->host);
/* NInoNonResident() == NInoIndexAllocPresent() */
if (NInoNonResident(ni)) {
/*
* Only unnamed $DATA attributes can be compressed or
* encrypted.
*/
if (ni->type == AT_DATA && !ni->name_len) {
/* If file is encrypted, deny access, just like NT4. */
if (NInoEncrypted(ni)) {
err = -EACCES;
goto err_out;
}
/* Compressed data streams are handled in compress.c. */
if (NInoCompressed(ni))
return ntfs_read_compressed_block(page);
}
/* Normal data stream. */
return ntfs_read_block(page);
}
/*
* Attribute is resident, implying it is not compressed or encrypted.
* This also means the attribute is smaller than an mft record and
* hence smaller than a page, so can simply zero out any pages with
* index above 0.
*/
if (unlikely(page->index > 0)) {
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr, 0, PAGE_CACHE_SIZE);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
goto done;
}
if (!NInoAttr(ni))
base_ni = ni;
else
base_ni = ni->ext.base_ntfs_ino;
/* Map, pin, and lock the mft record. */
mrec = map_mft_record(base_ni);
if (IS_ERR(mrec)) {
err = PTR_ERR(mrec);
goto err_out;
}
ctx = ntfs_attr_get_search_ctx(base_ni, mrec);
if (unlikely(!ctx)) {
err = -ENOMEM;
goto unm_err_out;
}
err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
CASE_SENSITIVE, 0, NULL, 0, ctx);
if (unlikely(err))
goto put_unm_err_out;
attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
read_lock_irqsave(&ni->size_lock, flags);
if (unlikely(attr_len > ni->initialized_size))
attr_len = ni->initialized_size;
read_unlock_irqrestore(&ni->size_lock, flags);
kaddr = kmap_atomic(page, KM_USER0);
/* Copy the data to the page. */
memcpy(kaddr, (u8*)ctx->attr +
le16_to_cpu(ctx->attr->data.resident.value_offset),
attr_len);
/* Zero the remainder of the page. */
memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
put_unm_err_out:
ntfs_attr_put_search_ctx(ctx);
unm_err_out:
unmap_mft_record(base_ni);
done:
SetPageUptodate(page);
err_out:
unlock_page(page);
return err;
}
#ifdef NTFS_RW
/**
* ntfs_write_block - write a @page to the backing store
* @page: page cache page to write out
* @wbc: writeback control structure
*
* This function is for writing pages belonging to non-resident, non-mst
* protected attributes to their backing store.
*
* For a page with buffers, map and write the dirty buffers asynchronously
* under page writeback. For a page without buffers, create buffers for the
* page, then proceed as above.
*
* If a page doesn't have buffers the page dirty state is definitive. If a page
* does have buffers, the page dirty state is just a hint, and the buffer dirty
* state is definitive. (A hint which has rules: dirty buffers against a clean
* page is illegal. Other combinations are legal and need to be handled. In
* particular a dirty page containing clean buffers for example.)
*
* Return 0 on success and -errno on error.
*
* Based on ntfs_read_block() and __block_write_full_page().
*/
static int ntfs_write_block(struct page *page, struct writeback_control *wbc)
{
VCN vcn;
LCN lcn;
s64 initialized_size;
loff_t i_size;
sector_t block, dblock, iblock;
struct inode *vi;
ntfs_inode *ni;
ntfs_volume *vol;
runlist_element *rl;
struct buffer_head *bh, *head;
unsigned long flags;
unsigned int blocksize, vcn_ofs;
int err;
BOOL need_end_writeback;
unsigned char blocksize_bits;
vi = page->mapping->host;
ni = NTFS_I(vi);
vol = ni->vol;
ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
"0x%lx.", ni->mft_no, ni->type, page->index);
BUG_ON(!NInoNonResident(ni));
BUG_ON(NInoMstProtected(ni));
blocksize_bits = vi->i_blkbits;
blocksize = 1 << blocksize_bits;
if (!page_has_buffers(page)) {
BUG_ON(!PageUptodate(page));
create_empty_buffers(page, blocksize,
(1 << BH_Uptodate) | (1 << BH_Dirty));
}
bh = head = page_buffers(page);
if (unlikely(!bh)) {
ntfs_warning(vol->sb, "Error allocating page buffers. "
"Redirtying page so we try again later.");
/*
* Put the page back on mapping->dirty_pages, but leave its
* buffer's dirty state as-is.
*/
redirty_page_for_writepage(wbc, page);
unlock_page(page);
return 0;
}
/* NOTE: Different naming scheme to ntfs_read_block()! */
/* The first block in the page. */
block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
read_lock_irqsave(&ni->size_lock, flags);
i_size = i_size_read(vi);
initialized_size = ni->initialized_size;
read_unlock_irqrestore(&ni->size_lock, flags);
/* The first out of bounds block for the data size. */
dblock = (i_size + blocksize - 1) >> blocksize_bits;
/* The last (fully or partially) initialized block. */
iblock = initialized_size >> blocksize_bits;
/*
* Be very careful. We have no exclusion from __set_page_dirty_buffers
* here, and the (potentially unmapped) buffers may become dirty at
* any time. If a buffer becomes dirty here after we've inspected it
* then we just miss that fact, and the page stays dirty.
*
* Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
* handle that here by just cleaning them.
*/
/*
* Loop through all the buffers in the page, mapping all the dirty
* buffers to disk addresses and handling any aliases from the
* underlying block device's mapping.
*/
rl = NULL;
err = 0;
do {
BOOL is_retry = FALSE;
if (unlikely(block >= dblock)) {
/*
* Mapped buffers outside i_size will occur, because
* this page can be outside i_size when there is a
* truncate in progress. The contents of such buffers
* were zeroed by ntfs_writepage().
*
* FIXME: What about the small race window where
* ntfs_writepage() has not done any clearing because
* the page was within i_size but before we get here,
* vmtruncate() modifies i_size?
*/
clear_buffer_dirty(bh);
set_buffer_uptodate(bh);
continue;
}
/* Clean buffers are not written out, so no need to map them. */
if (!buffer_dirty(bh))
continue;
/* Make sure we have enough initialized size. */
if (unlikely((block >= iblock) &&
(initialized_size < i_size))) {
/*
* If this page is fully outside initialized size, zero
* out all pages between the current initialized size
* and the current page. Just use ntfs_readpage() to do
* the zeroing transparently.
*/
if (block > iblock) {
// TODO:
// For each page do:
// - read_cache_page()
// Again for each page do:
// - wait_on_page_locked()
// - Check (PageUptodate(page) &&
// !PageError(page))
// Update initialized size in the attribute and
// in the inode.
// Again, for each page do:
// __set_page_dirty_buffers();
// page_cache_release()
// We don't need to wait on the writes.
// Update iblock.
}
/*
* The current page straddles initialized size. Zero
* all non-uptodate buffers and set them uptodate (and
* dirty?). Note, there aren't any non-uptodate buffers
* if the page is uptodate.
* FIXME: For an uptodate page, the buffers may need to
* be written out because they were not initialized on
* disk before.
*/
if (!PageUptodate(page)) {
// TODO:
// Zero any non-uptodate buffers up to i_size.
// Set them uptodate and dirty.
}
// TODO:
// Update initialized size in the attribute and in the
// inode (up to i_size).
// Update iblock.
// FIXME: This is inefficient. Try to batch the two
// size changes to happen in one go.
ntfs_error(vol->sb, "Writing beyond initialized size "
"is not supported yet. Sorry.");
err = -EOPNOTSUPP;
break;
// Do NOT set_buffer_new() BUT DO clear buffer range
// outside write request range.
// set_buffer_uptodate() on complete buffers as well as
// set_buffer_dirty().
}
/* No need to map buffers that are already mapped. */
if (buffer_mapped(bh))
continue;
/* Unmapped, dirty buffer. Need to map it. */
bh->b_bdev = vol->sb->s_bdev;
/* Convert block into corresponding vcn and offset. */
vcn = (VCN)block << blocksize_bits;
vcn_ofs = vcn & vol->cluster_size_mask;
vcn >>= vol->cluster_size_bits;
if (!rl) {
lock_retry_remap:
down_read(&ni->runlist.lock);
rl = ni->runlist.rl;
}
if (likely(rl != NULL)) {
/* Seek to element containing target vcn. */
while (rl->length && rl[1].vcn <= vcn)
rl++;
lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
} else
lcn = LCN_RL_NOT_MAPPED;
/* Successful remap. */
if (lcn >= 0) {
/* Setup buffer head to point to correct block. */
bh->b_blocknr = ((lcn << vol->cluster_size_bits) +
vcn_ofs) >> blocksize_bits;
set_buffer_mapped(bh);
continue;
}
/* It is a hole, need to instantiate it. */
if (lcn == LCN_HOLE) {
// TODO: Instantiate the hole.
// clear_buffer_new(bh);
// unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
ntfs_error(vol->sb, "Writing into sparse regions is "
"not supported yet. Sorry.");
err = -EOPNOTSUPP;
break;
}
/* If first try and runlist unmapped, map and retry. */
if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
is_retry = TRUE;
/*
* Attempt to map runlist, dropping lock for
* the duration.
*/
up_read(&ni->runlist.lock);
err = ntfs_map_runlist(ni, vcn);
if (likely(!err))
goto lock_retry_remap;
rl = NULL;
lcn = err;
}
/* Failed to map the buffer, even after retrying. */
bh->b_blocknr = -1;
ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
"attribute type 0x%x, vcn 0x%llx, offset 0x%x "
"because its location on disk could not be "
"determined%s (error code %lli).", ni->mft_no,
ni->type, (unsigned long long)vcn,
vcn_ofs, is_retry ? " even after "
"retrying" : "", (long long)lcn);
if (!err)
err = -EIO;
break;
} while (block++, (bh = bh->b_this_page) != head);
/* Release the lock if we took it. */
if (rl)
up_read(&ni->runlist.lock);
/* For the error case, need to reset bh to the beginning. */
bh = head;
/* Just an optimization, so ->readpage() isn't called later. */
if (unlikely(!PageUptodate(page))) {
int uptodate = 1;
do {
if (!buffer_uptodate(bh)) {
uptodate = 0;
bh = head;
break;
}
} while ((bh = bh->b_this_page) != head);
if (uptodate)
SetPageUptodate(page);
}
/* Setup all mapped, dirty buffers for async write i/o. */
do {
get_bh(bh);
if (buffer_mapped(bh) && buffer_dirty(bh)) {
lock_buffer(bh);
if (test_clear_buffer_dirty(bh)) {
BUG_ON(!buffer_uptodate(bh));
mark_buffer_async_write(bh);
} else
unlock_buffer(bh);
} else if (unlikely(err)) {
/*
* For the error case. The buffer may have been set
* dirty during attachment to a dirty page.
*/
if (err != -ENOMEM)
clear_buffer_dirty(bh);
}
} while ((bh = bh->b_this_page) != head);
if (unlikely(err)) {
// TODO: Remove the -EOPNOTSUPP check later on...
if (unlikely(err == -EOPNOTSUPP))
err = 0;
else if (err == -ENOMEM) {
ntfs_warning(vol->sb, "Error allocating memory. "
"Redirtying page so we try again "
"later.");
/*
* Put the page back on mapping->dirty_pages, but
* leave its buffer's dirty state as-is.
*/
redirty_page_for_writepage(wbc, page);
err = 0;
} else
SetPageError(page);
}
BUG_ON(PageWriteback(page));
set_page_writeback(page); /* Keeps try_to_free_buffers() away. */
unlock_page(page);
/*
* Submit the prepared buffers for i/o. Note the page is unlocked,
* and the async write i/o completion handler can end_page_writeback()
* at any time after the *first* submit_bh(). So the buffers can then
* disappear...
*/
need_end_writeback = TRUE;
do {
struct buffer_head *next = bh->b_this_page;
if (buffer_async_write(bh)) {
submit_bh(WRITE, bh);
need_end_writeback = FALSE;
}
put_bh(bh);
bh = next;
} while (bh != head);
/* If no i/o was started, need to end_page_writeback(). */
if (unlikely(need_end_writeback))
end_page_writeback(page);
ntfs_debug("Done.");
return err;
}
/**
* ntfs_write_mst_block - write a @page to the backing store
* @page: page cache page to write out
* @wbc: writeback control structure
*
* This function is for writing pages belonging to non-resident, mst protected
* attributes to their backing store. The only supported attributes are index
* allocation and $MFT/$DATA. Both directory inodes and index inodes are
* supported for the index allocation case.
*
* The page must remain locked for the duration of the write because we apply
* the mst fixups, write, and then undo the fixups, so if we were to unlock the
* page before undoing the fixups, any other user of the page will see the
* page contents as corrupt.
*
* We clear the page uptodate flag for the duration of the function to ensure
* exclusion for the $MFT/$DATA case against someone mapping an mft record we
* are about to apply the mst fixups to.
*
* Return 0 on success and -errno on error.
*
* Based on ntfs_write_block(), ntfs_mft_writepage(), and
* write_mft_record_nolock().
*/
static int ntfs_write_mst_block(struct page *page,
struct writeback_control *wbc)
{
sector_t block, dblock, rec_block;
struct inode *vi = page->mapping->host;
ntfs_inode *ni = NTFS_I(vi);
ntfs_volume *vol = ni->vol;
u8 *kaddr;
unsigned char bh_size_bits = vi->i_blkbits;
unsigned int bh_size = 1 << bh_size_bits;
unsigned int rec_size = ni->itype.index.block_size;
ntfs_inode *locked_nis[PAGE_CACHE_SIZE / rec_size];
struct buffer_head *bh, *head, *tbh, *rec_start_bh;
int max_bhs = PAGE_CACHE_SIZE / bh_size;
struct buffer_head *bhs[max_bhs];
runlist_element *rl;
int i, nr_locked_nis, nr_recs, nr_bhs, bhs_per_rec, err, err2;
unsigned rec_size_bits;
BOOL sync, is_mft, page_is_dirty, rec_is_dirty;
ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
"0x%lx.", vi->i_ino, ni->type, page->index);
BUG_ON(!NInoNonResident(ni));
BUG_ON(!NInoMstProtected(ni));
is_mft = (S_ISREG(vi->i_mode) && !vi->i_ino);
/*
* NOTE: ntfs_write_mst_block() would be called for $MFTMirr if a page
* in its page cache were to be marked dirty. However this should
* never happen with the current driver and considering we do not
* handle this case here we do want to BUG(), at least for now.
*/
BUG_ON(!(is_mft || S_ISDIR(vi->i_mode) ||
(NInoAttr(ni) && ni->type == AT_INDEX_ALLOCATION)));
BUG_ON(!max_bhs);
/* Were we called for sync purposes? */
sync = (wbc->sync_mode == WB_SYNC_ALL);
/* Make sure we have mapped buffers. */
BUG_ON(!page_has_buffers(page));
bh = head = page_buffers(page);
BUG_ON(!bh);
rec_size_bits = ni->itype.index.block_size_bits;
BUG_ON(!(PAGE_CACHE_SIZE >> rec_size_bits));
bhs_per_rec = rec_size >> bh_size_bits;
BUG_ON(!bhs_per_rec);
/* The first block in the page. */
rec_block = block = (sector_t)page->index <<
(PAGE_CACHE_SHIFT - bh_size_bits);
/* The first out of bounds block for the data size. */
dblock = (i_size_read(vi) + bh_size - 1) >> bh_size_bits;
rl = NULL;
err = err2 = nr_bhs = nr_recs = nr_locked_nis = 0;
page_is_dirty = rec_is_dirty = FALSE;
rec_start_bh = NULL;
do {
BOOL is_retry = FALSE;
if (likely(block < rec_block)) {
if (unlikely(block >= dblock)) {
clear_buffer_dirty(bh);
set_buffer_uptodate(bh);
continue;
}
/*
* This block is not the first one in the record. We
* ignore the buffer's dirty state because we could
* have raced with a parallel mark_ntfs_record_dirty().
*/
if (!rec_is_dirty)
continue;
if (unlikely(err2)) {
if (err2 != -ENOMEM)
clear_buffer_dirty(bh);
continue;
}
} else /* if (block == rec_block) */ {
BUG_ON(block > rec_block);
/* This block is the first one in the record. */
rec_block += bhs_per_rec;
err2 = 0;
if (unlikely(block >= dblock)) {
clear_buffer_dirty(bh);
continue;
}
if (!buffer_dirty(bh)) {
/* Clean records are not written out. */
rec_is_dirty = FALSE;
continue;
}
rec_is_dirty = TRUE;
rec_start_bh = bh;
}
/* Need to map the buffer if it is not mapped already. */
if (unlikely(!buffer_mapped(bh))) {
VCN vcn;
LCN lcn;
unsigned int vcn_ofs;
/* Obtain the vcn and offset of the current block. */
vcn = (VCN)block << bh_size_bits;
vcn_ofs = vcn & vol->cluster_size_mask;
vcn >>= vol->cluster_size_bits;
if (!rl) {
lock_retry_remap:
down_read(&ni->runlist.lock);
rl = ni->runlist.rl;
}
if (likely(rl != NULL)) {
/* Seek to element containing target vcn. */
while (rl->length && rl[1].vcn <= vcn)
rl++;
lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
} else
lcn = LCN_RL_NOT_MAPPED;
/* Successful remap. */
if (likely(lcn >= 0)) {
/* Setup buffer head to correct block. */
bh->b_blocknr = ((lcn <<
vol->cluster_size_bits) +
vcn_ofs) >> bh_size_bits;
set_buffer_mapped(bh);
} else {
/*
* Remap failed. Retry to map the runlist once
* unless we are working on $MFT which always
* has the whole of its runlist in memory.
*/
if (!is_mft && !is_retry &&
lcn == LCN_RL_NOT_MAPPED) {
is_retry = TRUE;
/*
* Attempt to map runlist, dropping
* lock for the duration.
*/
up_read(&ni->runlist.lock);
err2 = ntfs_map_runlist(ni, vcn);
if (likely(!err2))
goto lock_retry_remap;
if (err2 == -ENOMEM)
page_is_dirty = TRUE;
lcn = err2;
} else
err2 = -EIO;
/* Hard error. Abort writing this record. */
if (!err || err == -ENOMEM)
err = err2;
bh->b_blocknr = -1;
ntfs_error(vol->sb, "Cannot write ntfs record "
"0x%llx (inode 0x%lx, "
"attribute type 0x%x) because "
"its location on disk could "
"not be determined (error "
"code %lli).", (s64)block <<
bh_size_bits >>
vol->mft_record_size_bits,
ni->mft_no, ni->type,
(long long)lcn);
/*
* If this is not the first buffer, remove the
* buffers in this record from the list of
* buffers to write and clear their dirty bit
* if not error -ENOMEM.
*/
if (rec_start_bh != bh) {
while (bhs[--nr_bhs] != rec_start_bh)
;
if (err2 != -ENOMEM) {
do {
clear_buffer_dirty(
rec_start_bh);
} while ((rec_start_bh =
rec_start_bh->
b_this_page) !=
bh);
}
}
continue;
}
}
BUG_ON(!buffer_uptodate(bh));
BUG_ON(nr_bhs >= max_bhs);
bhs[nr_bhs++] = bh;
} while (block++, (bh = bh->b_this_page) != head);
if (unlikely(rl))
up_read(&ni->runlist.lock);
/* If there were no dirty buffers, we are done. */
if (!nr_bhs)
goto done;
/* Map the page so we can access its contents. */
kaddr = kmap(page);
/* Clear the page uptodate flag whilst the mst fixups are applied. */
BUG_ON(!PageUptodate(page));
ClearPageUptodate(page);
for (i = 0; i < nr_bhs; i++) {
unsigned int ofs;
/* Skip buffers which are not at the beginning of records. */
if (i % bhs_per_rec)
continue;
tbh = bhs[i];
ofs = bh_offset(tbh);
if (is_mft) {
ntfs_inode *tni;
unsigned long mft_no;
/* Get the mft record number. */
mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs)
>> rec_size_bits;
/* Check whether to write this mft record. */
tni = NULL;
if (!ntfs_may_write_mft_record(vol, mft_no,
(MFT_RECORD*)(kaddr + ofs), &tni)) {
/*
* The record should not be written. This
* means we need to redirty the page before
* returning.
*/
page_is_dirty = TRUE;
/*
* Remove the buffers in this mft record from
* the list of buffers to write.
*/
do {
bhs[i] = NULL;
} while (++i % bhs_per_rec);
continue;
}
/*
* The record should be written. If a locked ntfs
* inode was returned, add it to the array of locked
* ntfs inodes.
*/
if (tni)
locked_nis[nr_locked_nis++] = tni;
}
/* Apply the mst protection fixups. */
err2 = pre_write_mst_fixup((NTFS_RECORD*)(kaddr + ofs),
rec_size);
if (unlikely(err2)) {
if (!err || err == -ENOMEM)
err = -EIO;
ntfs_error(vol->sb, "Failed to apply mst fixups "
"(inode 0x%lx, attribute type 0x%x, "
"page index 0x%lx, page offset 0x%x)!"
" Unmount and run chkdsk.", vi->i_ino,
ni->type, page->index, ofs);
/*
* Mark all the buffers in this record clean as we do
* not want to write corrupt data to disk.
*/
do {
clear_buffer_dirty(bhs[i]);
bhs[i] = NULL;
} while (++i % bhs_per_rec);
continue;
}
nr_recs++;
}
/* If no records are to be written out, we are done. */
if (!nr_recs)
goto unm_done;
flush_dcache_page(page);
/* Lock buffers and start synchronous write i/o on them. */
for (i = 0; i < nr_bhs; i++) {
tbh = bhs[i];
if (!tbh)
continue;
if (unlikely(test_set_buffer_locked(tbh)))
BUG();
/* The buffer dirty state is now irrelevant, just clean it. */
clear_buffer_dirty(tbh);
BUG_ON(!buffer_uptodate(tbh));
BUG_ON(!buffer_mapped(tbh));
get_bh(tbh);
tbh->b_end_io = end_buffer_write_sync;
submit_bh(WRITE, tbh);
}
/* Synchronize the mft mirror now if not @sync. */
if (is_mft && !sync)
goto do_mirror;
do_wait:
/* Wait on i/o completion of buffers. */
for (i = 0; i < nr_bhs; i++) {
tbh = bhs[i];
if (!tbh)
continue;
wait_on_buffer(tbh);
if (unlikely(!buffer_uptodate(tbh))) {
ntfs_error(vol->sb, "I/O error while writing ntfs "
"record buffer (inode 0x%lx, "
"attribute type 0x%x, page index "
"0x%lx, page offset 0x%lx)! Unmount "
"and run chkdsk.", vi->i_ino, ni->type,
page->index, bh_offset(tbh));
if (!err || err == -ENOMEM)
err = -EIO;
/*
* Set the buffer uptodate so the page and buffer
* states do not become out of sync.
*/
set_buffer_uptodate(tbh);
}
}
/* If @sync, now synchronize the mft mirror. */
if (is_mft && sync) {
do_mirror:
for (i = 0; i < nr_bhs; i++) {
unsigned long mft_no;
unsigned int ofs;
/*
* Skip buffers which are not at the beginning of
* records.
*/
if (i % bhs_per_rec)
continue;
tbh = bhs[i];
/* Skip removed buffers (and hence records). */
if (!tbh)
continue;
ofs = bh_offset(tbh);
/* Get the mft record number. */
mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs)
>> rec_size_bits;
if (mft_no < vol->mftmirr_size)
ntfs_sync_mft_mirror(vol, mft_no,
(MFT_RECORD*)(kaddr + ofs),
sync);
}
if (!sync)
goto do_wait;
}
/* Remove the mst protection fixups again. */
for (i = 0; i < nr_bhs; i++) {
if (!(i % bhs_per_rec)) {
tbh = bhs[i];
if (!tbh)
continue;
post_write_mst_fixup((NTFS_RECORD*)(kaddr +
bh_offset(tbh)));
}
}
flush_dcache_page(page);
unm_done:
/* Unlock any locked inodes. */
while (nr_locked_nis-- > 0) {
ntfs_inode *tni, *base_tni;
tni = locked_nis[nr_locked_nis];
/* Get the base inode. */
down(&tni->extent_lock);
if (tni->nr_extents >= 0)
base_tni = tni;
else {
base_tni = tni->ext.base_ntfs_ino;
BUG_ON(!base_tni);
}
up(&tni->extent_lock);
ntfs_debug("Unlocking %s inode 0x%lx.",
tni == base_tni ? "base" : "extent",
tni->mft_no);
up(&tni->mrec_lock);
atomic_dec(&tni->count);
iput(VFS_I(base_tni));
}
SetPageUptodate(page);
kunmap(page);
done:
if (unlikely(err && err != -ENOMEM)) {
/*
* Set page error if there is only one ntfs record in the page.
* Otherwise we would loose per-record granularity.
*/
if (ni->itype.index.block_size == PAGE_CACHE_SIZE)
SetPageError(page);
NVolSetErrors(vol);
}
if (page_is_dirty) {
ntfs_debug("Page still contains one or more dirty ntfs "
"records. Redirtying the page starting at "
"record 0x%lx.", page->index <<
(PAGE_CACHE_SHIFT - rec_size_bits));
redirty_page_for_writepage(wbc, page);
unlock_page(page);
} else {
/*
* Keep the VM happy. This must be done otherwise the
* radix-tree tag PAGECACHE_TAG_DIRTY remains set even though
* the page is clean.
*/
BUG_ON(PageWriteback(page));
set_page_writeback(page);
unlock_page(page);
end_page_writeback(page);
}
if (likely(!err))
ntfs_debug("Done.");
return err;
}
/**
* ntfs_writepage - write a @page to the backing store
* @page: page cache page to write out
* @wbc: writeback control structure
*
* This is called from the VM when it wants to have a dirty ntfs page cache
* page cleaned. The VM has already locked the page and marked it clean.
*
* For non-resident attributes, ntfs_writepage() writes the @page by calling
* the ntfs version of the generic block_write_full_page() function,
* ntfs_write_block(), which in turn if necessary creates and writes the
* buffers associated with the page asynchronously.
*
* For resident attributes, OTOH, ntfs_writepage() writes the @page by copying
* the data to the mft record (which at this stage is most likely in memory).
* The mft record is then marked dirty and written out asynchronously via the
* vfs inode dirty code path for the inode the mft record belongs to or via the
* vm page dirty code path for the page the mft record is in.
*
* Based on ntfs_readpage() and fs/buffer.c::block_write_full_page().
*
* Return 0 on success and -errno on error.
*/
static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
{
loff_t i_size;
struct inode *vi = page->mapping->host;
ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
char *kaddr;
ntfs_attr_search_ctx *ctx = NULL;
MFT_RECORD *m = NULL;
u32 attr_len;
int err;
BUG_ON(!PageLocked(page));
i_size = i_size_read(vi);
/* Is the page fully outside i_size? (truncate in progress) */
if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>
PAGE_CACHE_SHIFT)) {
/*
* The page may have dirty, unmapped buffers. Make them
* freeable here, so the page does not leak.
*/
block_invalidatepage(page, 0);
unlock_page(page);
ntfs_debug("Write outside i_size - truncated?");
return 0;
}
/* NInoNonResident() == NInoIndexAllocPresent() */
if (NInoNonResident(ni)) {
/*
* Only unnamed $DATA attributes can be compressed, encrypted,
* and/or sparse.
*/
if (ni->type == AT_DATA && !ni->name_len) {
/* If file is encrypted, deny access, just like NT4. */
if (NInoEncrypted(ni)) {
unlock_page(page);
ntfs_debug("Denying write access to encrypted "
"file.");
return -EACCES;
}
/* Compressed data streams are handled in compress.c. */
if (NInoCompressed(ni)) {
// TODO: Implement and replace this check with
// return ntfs_write_compressed_block(page);
unlock_page(page);
ntfs_error(vi->i_sb, "Writing to compressed "
"files is not supported yet. "
"Sorry.");
return -EOPNOTSUPP;
}
// TODO: Implement and remove this check.
if (NInoSparse(ni)) {
unlock_page(page);
ntfs_error(vi->i_sb, "Writing to sparse files "
"is not supported yet. Sorry.");
return -EOPNOTSUPP;
}
}
/* We have to zero every time due to mmap-at-end-of-file. */
if (page->index >= (i_size >> PAGE_CACHE_SHIFT)) {
/* The page straddles i_size. */
unsigned int ofs = i_size & ~PAGE_CACHE_MASK;
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + ofs, 0, PAGE_CACHE_SIZE - ofs);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
}
/* Handle mst protected attributes. */
if (NInoMstProtected(ni))
return ntfs_write_mst_block(page, wbc);
/* Normal data stream. */
return ntfs_write_block(page, wbc);
}
/*
* Attribute is resident, implying it is not compressed, encrypted,
* sparse, or mst protected. This also means the attribute is smaller
* than an mft record and hence smaller than a page, so can simply
* return error on any pages with index above 0.
*/
BUG_ON(page_has_buffers(page));
BUG_ON(!PageUptodate(page));
if (unlikely(page->index > 0)) {
ntfs_error(vi->i_sb, "BUG()! page->index (0x%lx) > 0. "
"Aborting write.", page->index);
BUG_ON(PageWriteback(page));
set_page_writeback(page);
unlock_page(page);
end_page_writeback(page);
return -EIO;
}
if (!NInoAttr(ni))
base_ni = ni;
else
base_ni = ni->ext.base_ntfs_ino;
/* Map, pin, and lock the mft record. */
m = map_mft_record(base_ni);
if (IS_ERR(m)) {
err = PTR_ERR(m);
m = NULL;
ctx = NULL;
goto err_out;
}
ctx = ntfs_attr_get_search_ctx(base_ni, m);
if (unlikely(!ctx)) {
err = -ENOMEM;
goto err_out;
}
err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
CASE_SENSITIVE, 0, NULL, 0, ctx);
if (unlikely(err))
goto err_out;
/*
* Keep the VM happy. This must be done otherwise the radix-tree tag
* PAGECACHE_TAG_DIRTY remains set even though the page is clean.
*/
BUG_ON(PageWriteback(page));
set_page_writeback(page);
unlock_page(page);
/*
* Here, we don't need to zero the out of bounds area everytime because
* the below memcpy() already takes care of the mmap-at-end-of-file
* requirements. If the file is converted to a non-resident one, then
* the code path use is switched to the non-resident one where the
* zeroing happens on each ntfs_writepage() invocation.
*
* The above also applies nicely when i_size is decreased.
*
* When i_size is increased, the memory between the old and new i_size
* _must_ be zeroed (or overwritten with new data). Otherwise we will
* expose data to userspace/disk which should never have been exposed.
*
* FIXME: Ensure that i_size increases do the zeroing/overwriting and
* if we cannot guarantee that, then enable the zeroing below. If the
* zeroing below is enabled, we MUST move the unlock_page() from above
* to after the kunmap_atomic(), i.e. just before the
* end_page_writeback().
* UPDATE: ntfs_prepare/commit_write() do the zeroing on i_size
* increases for resident attributes so those are ok.
* TODO: ntfs_truncate(), others?
*/
attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
i_size = i_size_read(vi);
if (unlikely(attr_len > i_size)) {
attr_len = i_size;
ctx->attr->data.resident.value_length = cpu_to_le32(attr_len);
}
kaddr = kmap_atomic(page, KM_USER0);
/* Copy the data from the page to the mft record. */
memcpy((u8*)ctx->attr +
le16_to_cpu(ctx->attr->data.resident.value_offset),
kaddr, attr_len);
flush_dcache_mft_record_page(ctx->ntfs_ino);
/* Zero out of bounds area in the page cache page. */
memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
end_page_writeback(page);
/* Mark the mft record dirty, so it gets written back. */
mark_mft_record_dirty(ctx->ntfs_ino);
ntfs_attr_put_search_ctx(ctx);
unmap_mft_record(base_ni);
return 0;
err_out:
if (err == -ENOMEM) {
ntfs_warning(vi->i_sb, "Error allocating memory. Redirtying "
"page so we try again later.");
/*
* Put the page back on mapping->dirty_pages, but leave its
* buffers' dirty state as-is.
*/
redirty_page_for_writepage(wbc, page);
err = 0;
} else {
ntfs_error(vi->i_sb, "Resident attribute write failed with "
"error %i.", err);
SetPageError(page);
NVolSetErrors(ni->vol);
make_bad_inode(vi);
}
unlock_page(page);
if (ctx)
ntfs_attr_put_search_ctx(ctx);
if (m)
unmap_mft_record(base_ni);
return err;
}
/**
* ntfs_prepare_nonresident_write -
*
*/
static int ntfs_prepare_nonresident_write(struct page *page,
unsigned from, unsigned to)
{
VCN vcn;
LCN lcn;
s64 initialized_size;
loff_t i_size;
sector_t block, ablock, iblock;
struct inode *vi;
ntfs_inode *ni;
ntfs_volume *vol;
runlist_element *rl;
struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
unsigned long flags;
unsigned int vcn_ofs, block_start, block_end, blocksize;
int err;
BOOL is_retry;
unsigned char blocksize_bits;
vi = page->mapping->host;
ni = NTFS_I(vi);
vol = ni->vol;
ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
"0x%lx, from = %u, to = %u.", ni->mft_no, ni->type,
page->index, from, to);
BUG_ON(!NInoNonResident(ni));
blocksize_bits = vi->i_blkbits;
blocksize = 1 << blocksize_bits;
/*
* create_empty_buffers() will create uptodate/dirty buffers if the
* page is uptodate/dirty.
*/
if (!page_has_buffers(page))
create_empty_buffers(page, blocksize, 0);
bh = head = page_buffers(page);
if (unlikely(!bh))
return -ENOMEM;
/* The first block in the page. */
block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
read_lock_irqsave(&ni->size_lock, flags);
/*
* The first out of bounds block for the allocated size. No need to
* round up as allocated_size is in multiples of cluster size and the
* minimum cluster size is 512 bytes, which is equal to the smallest
* blocksize.
*/
ablock = ni->allocated_size >> blocksize_bits;
i_size = i_size_read(vi);
initialized_size = ni->initialized_size;
read_unlock_irqrestore(&ni->size_lock, flags);
/* The last (fully or partially) initialized block. */
iblock = initialized_size >> blocksize_bits;
/* Loop through all the buffers in the page. */
block_start = 0;
rl = NULL;
err = 0;
do {
block_end = block_start + blocksize;
/*
* If buffer @bh is outside the write, just mark it uptodate
* if the page is uptodate and continue with the next buffer.
*/
if (block_end <= from || block_start >= to) {
if (PageUptodate(page)) {
if (!buffer_uptodate(bh))
set_buffer_uptodate(bh);
}
continue;
}
/*
* @bh is at least partially being written to.
* Make sure it is not marked as new.
*/
//if (buffer_new(bh))
// clear_buffer_new(bh);
if (block >= ablock) {
// TODO: block is above allocated_size, need to
// allocate it. Best done in one go to accommodate not
// only block but all above blocks up to and including:
// ((page->index << PAGE_CACHE_SHIFT) + to + blocksize
// - 1) >> blobksize_bits. Obviously will need to round
// up to next cluster boundary, too. This should be
// done with a helper function, so it can be reused.
ntfs_error(vol->sb, "Writing beyond allocated size "
"is not supported yet. Sorry.");
err = -EOPNOTSUPP;
goto err_out;
// Need to update ablock.
// Need to set_buffer_new() on all block bhs that are
// newly allocated.
}
/*
* Now we have enough allocated size to fulfill the whole
* request, i.e. block < ablock is true.
*/
if (unlikely((block >= iblock) &&
(initialized_size < i_size))) {
/*
* If this page is fully outside initialized size, zero
* out all pages between the current initialized size
* and the current page. Just use ntfs_readpage() to do
* the zeroing transparently.
*/
if (block > iblock) {
// TODO:
// For each page do:
// - read_cache_page()
// Again for each page do:
// - wait_on_page_locked()
// - Check (PageUptodate(page) &&
// !PageError(page))
// Update initialized size in the attribute and
// in the inode.
// Again, for each page do:
// __set_page_dirty_buffers();
// page_cache_release()
// We don't need to wait on the writes.
// Update iblock.
}
/*
* The current page straddles initialized size. Zero
* all non-uptodate buffers and set them uptodate (and
* dirty?). Note, there aren't any non-uptodate buffers
* if the page is uptodate.
* FIXME: For an uptodate page, the buffers may need to
* be written out because they were not initialized on
* disk before.
*/
if (!PageUptodate(page)) {
// TODO:
// Zero any non-uptodate buffers up to i_size.
// Set them uptodate and dirty.
}
// TODO:
// Update initialized size in the attribute and in the
// inode (up to i_size).
// Update iblock.
// FIXME: This is inefficient. Try to batch the two
// size changes to happen in one go.
ntfs_error(vol->sb, "Writing beyond initialized size "
"is not supported yet. Sorry.");
err = -EOPNOTSUPP;
goto err_out;
// Do NOT set_buffer_new() BUT DO clear buffer range
// outside write request range.
// set_buffer_uptodate() on complete buffers as well as
// set_buffer_dirty().
}
/* Need to map unmapped buffers. */
if (!buffer_mapped(bh)) {
/* Unmapped buffer. Need to map it. */
bh->b_bdev = vol->sb->s_bdev;
/* Convert block into corresponding vcn and offset. */
vcn = (VCN)block << blocksize_bits >>
vol->cluster_size_bits;
vcn_ofs = ((VCN)block << blocksize_bits) &
vol->cluster_size_mask;
is_retry = FALSE;
if (!rl) {
lock_retry_remap:
down_read(&ni->runlist.lock);
rl = ni->runlist.rl;
}
if (likely(rl != NULL)) {
/* Seek to element containing target vcn. */
while (rl->length && rl[1].vcn <= vcn)
rl++;
lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
} else
lcn = LCN_RL_NOT_MAPPED;
if (unlikely(lcn < 0)) {
/*
* We extended the attribute allocation above.
* If we hit an ENOENT here it means that the
* allocation was insufficient which is a bug.
*/
BUG_ON(lcn == LCN_ENOENT);
/* It is a hole, need to instantiate it. */
if (lcn == LCN_HOLE) {
// TODO: Instantiate the hole.
// clear_buffer_new(bh);
// unmap_underlying_metadata(bh->b_bdev,
// bh->b_blocknr);
// For non-uptodate buffers, need to
// zero out the region outside the
// request in this bh or all bhs,
// depending on what we implemented
// above.
// Need to flush_dcache_page().
// Or could use set_buffer_new()
// instead?
ntfs_error(vol->sb, "Writing into "
"sparse regions is "
"not supported yet. "
"Sorry.");
err = -EOPNOTSUPP;
goto err_out;
} else if (!is_retry &&
lcn == LCN_RL_NOT_MAPPED) {
is_retry = TRUE;
/*
* Attempt to map runlist, dropping
* lock for the duration.
*/
up_read(&ni->runlist.lock);
err = ntfs_map_runlist(ni, vcn);
if (likely(!err))
goto lock_retry_remap;
rl = NULL;
lcn = err;
}
/*
* Failed to map the buffer, even after
* retrying.
*/
bh->b_blocknr = -1;
ntfs_error(vol->sb, "Failed to write to inode "
"0x%lx, attribute type 0x%x, "
"vcn 0x%llx, offset 0x%x "
"because its location on disk "
"could not be determined%s "
"(error code %lli).",
ni->mft_no, ni->type,
(unsigned long long)vcn,
vcn_ofs, is_retry ? " even "
"after retrying" : "",
(long long)lcn);
if (!err)
err = -EIO;
goto err_out;
}
/* We now have a successful remap, i.e. lcn >= 0. */
/* Setup buffer head to correct block. */
bh->b_blocknr = ((lcn << vol->cluster_size_bits)
+ vcn_ofs) >> blocksize_bits;
set_buffer_mapped(bh);
// FIXME: Something analogous to this is needed for
// each newly allocated block, i.e. BH_New.
// FIXME: Might need to take this out of the
// if (!buffer_mapped(bh)) {}, depending on how we
// implement things during the allocated_size and
// initialized_size extension code above.
if (buffer_new(bh)) {
clear_buffer_new(bh);
unmap_underlying_metadata(bh->b_bdev,
bh->b_blocknr);
if (PageUptodate(page)) {
set_buffer_uptodate(bh);
continue;
}
/*
* Page is _not_ uptodate, zero surrounding
* region. NOTE: This is how we decide if to
* zero or not!
*/
if (block_end > to || block_start < from) {
void *kaddr;
kaddr = kmap_atomic(page, KM_USER0);
if (block_end > to)
memset(kaddr + to, 0,
block_end - to);
if (block_start < from)
memset(kaddr + block_start, 0,
from -
block_start);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
}
continue;
}
}
/* @bh is mapped, set it uptodate if the page is uptodate. */
if (PageUptodate(page)) {
if (!buffer_uptodate(bh))
set_buffer_uptodate(bh);
continue;
}
/*
* The page is not uptodate. The buffer is mapped. If it is not
* uptodate, and it is only partially being written to, we need
* to read the buffer in before the write, i.e. right now.
*/
if (!buffer_uptodate(bh) &&
(block_start < from || block_end > to)) {
ll_rw_block(READ, 1, &bh);
*wait_bh++ = bh;
}
} while (block++, block_start = block_end,
(bh = bh->b_this_page) != head);
/* Release the lock if we took it. */
if (rl) {
up_read(&ni->runlist.lock);
rl = NULL;
}
/* If we issued read requests, let them complete. */
while (wait_bh > wait) {
wait_on_buffer(*--wait_bh);
if (!buffer_uptodate(*wait_bh))
return -EIO;
}
ntfs_debug("Done.");
return 0;
err_out:
/*
* Zero out any newly allocated blocks to avoid exposing stale data.
* If BH_New is set, we know that the block was newly allocated in the
* above loop.
* FIXME: What about initialized_size increments? Have we done all the
* required zeroing above? If not this error handling is broken, and
* in particular the if (block_end <= from) check is completely bogus.
*/
bh = head;
block_start = 0;
is_retry = FALSE;
do {
block_end = block_start + blocksize;
if (block_end <= from)
continue;
if (block_start >= to)
break;
if (buffer_new(bh)) {
void *kaddr;
clear_buffer_new(bh);
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + block_start, 0, bh->b_size);
kunmap_atomic(kaddr, KM_USER0);
set_buffer_uptodate(bh);
mark_buffer_dirty(bh);
is_retry = TRUE;
}
} while (block_start = block_end, (bh = bh->b_this_page) != head);
if (is_retry)
flush_dcache_page(page);
if (rl)
up_read(&ni->runlist.lock);
return err;
}
/**
* ntfs_prepare_write - prepare a page for receiving data
*
* This is called from generic_file_write() with i_sem held on the inode
* (@page->mapping->host). The @page is locked but not kmap()ped. The source
* data has not yet been copied into the @page.
*
* Need to extend the attribute/fill in holes if necessary, create blocks and
* make partially overwritten blocks uptodate,
*
* i_size is not to be modified yet.
*
* Return 0 on success or -errno on error.
*
* Should be using block_prepare_write() [support for sparse files] or
* cont_prepare_write() [no support for sparse files]. Cannot do that due to
* ntfs specifics but can look at them for implementation guidance.
*
* Note: In the range, @from is inclusive and @to is exclusive, i.e. @from is
* the first byte in the page that will be written to and @to is the first byte
* after the last byte that will be written to.
*/
static int ntfs_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
s64 new_size;
loff_t i_size;
struct inode *vi = page->mapping->host;
ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
ntfs_volume *vol = ni->vol;
ntfs_attr_search_ctx *ctx = NULL;
MFT_RECORD *m = NULL;
ATTR_RECORD *a;
u8 *kaddr;
u32 attr_len;
int err;
ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
"0x%lx, from = %u, to = %u.", vi->i_ino, ni->type,
page->index, from, to);
BUG_ON(!PageLocked(page));
BUG_ON(from > PAGE_CACHE_SIZE);
BUG_ON(to > PAGE_CACHE_SIZE);
BUG_ON(from > to);
BUG_ON(NInoMstProtected(ni));
/*
* If a previous ntfs_truncate() failed, repeat it and abort if it
* fails again.
*/
if (unlikely(NInoTruncateFailed(ni))) {
down_write(&vi->i_alloc_sem);
err = ntfs_truncate(vi);
up_write(&vi->i_alloc_sem);
if (err || NInoTruncateFailed(ni)) {
if (!err)
err = -EIO;
goto err_out;
}
}
/* If the attribute is not resident, deal with it elsewhere. */
if (NInoNonResident(ni)) {
/*
* Only unnamed $DATA attributes can be compressed, encrypted,
* and/or sparse.
*/
if (ni->type == AT_DATA && !ni->name_len) {
/* If file is encrypted, deny access, just like NT4. */
if (NInoEncrypted(ni)) {
ntfs_debug("Denying write access to encrypted "
"file.");
return -EACCES;
}
/* Compressed data streams are handled in compress.c. */
if (NInoCompressed(ni)) {
// TODO: Implement and replace this check with
// return ntfs_write_compressed_block(page);
ntfs_error(vi->i_sb, "Writing to compressed "
"files is not supported yet. "
"Sorry.");
return -EOPNOTSUPP;
}
// TODO: Implement and remove this check.
if (NInoSparse(ni)) {
ntfs_error(vi->i_sb, "Writing to sparse files "
"is not supported yet. Sorry.");
return -EOPNOTSUPP;
}
}
/* Normal data stream. */
return ntfs_prepare_nonresident_write(page, from, to);
}
/*
* Attribute is resident, implying it is not compressed, encrypted, or
* sparse.
*/
BUG_ON(page_has_buffers(page));
new_size = ((s64)page->index << PAGE_CACHE_SHIFT) + to;
/* If we do not need to resize the attribute allocation we are done. */
if (new_size <= i_size_read(vi))
goto done;
/* Map, pin, and lock the (base) mft record. */
if (!NInoAttr(ni))
base_ni = ni;
else
base_ni = ni->ext.base_ntfs_ino;
m = map_mft_record(base_ni);
if (IS_ERR(m)) {
err = PTR_ERR(m);
m = NULL;
ctx = NULL;
goto err_out;
}
ctx = ntfs_attr_get_search_ctx(base_ni, m);
if (unlikely(!ctx)) {
err = -ENOMEM;
goto err_out;
}
err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
CASE_SENSITIVE, 0, NULL, 0, ctx);
if (unlikely(err)) {
if (err == -ENOENT)
err = -EIO;
goto err_out;
}
m = ctx->mrec;
a = ctx->attr;
/* The total length of the attribute value. */
attr_len = le32_to_cpu(a->data.resident.value_length);
/* Fix an eventual previous failure of ntfs_commit_write(). */
i_size = i_size_read(vi);
if (unlikely(attr_len > i_size)) {
attr_len = i_size;
a->data.resident.value_length = cpu_to_le32(attr_len);
}
/* If we do not need to resize the attribute allocation we are done. */
if (new_size <= attr_len)
goto done_unm;
/* Check if new size is allowed in $AttrDef. */
err = ntfs_attr_size_bounds_check(vol, ni->type, new_size);
if (unlikely(err)) {
if (err == -ERANGE) {
ntfs_error(vol->sb, "Write would cause the inode "
"0x%lx to exceed the maximum size for "
"its attribute type (0x%x). Aborting "
"write.", vi->i_ino,
le32_to_cpu(ni->type));
} else {
ntfs_error(vol->sb, "Inode 0x%lx has unknown "
"attribute type 0x%x. Aborting "
"write.", vi->i_ino,
le32_to_cpu(ni->type));
err = -EIO;
}
goto err_out2;
}
/*
* Extend the attribute record to be able to store the new attribute
* size.
*/
if (new_size >= vol->mft_record_size || ntfs_attr_record_resize(m, a,
le16_to_cpu(a->data.resident.value_offset) +
new_size)) {
/* Not enough space in the mft record. */
ntfs_error(vol->sb, "Not enough space in the mft record for "
"the resized attribute value. This is not "
"supported yet. Aborting write.");
err = -EOPNOTSUPP;
goto err_out2;
}
/*
* We have enough space in the mft record to fit the write. This
* implies the attribute is smaller than the mft record and hence the
* attribute must be in a single page and hence page->index must be 0.
*/
BUG_ON(page->index);
/*
* If the beginning of the write is past the old size, enlarge the
* attribute value up to the beginning of the write and fill it with
* zeroes.
*/
if (from > attr_len) {
memset((u8*)a + le16_to_cpu(a->data.resident.value_offset) +
attr_len, 0, from - attr_len);
a->data.resident.value_length = cpu_to_le32(from);
/* Zero the corresponding area in the page as well. */
if (PageUptodate(page)) {
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + attr_len, 0, from - attr_len);
kunmap_atomic(kaddr, KM_USER0);
flush_dcache_page(page);
}
}
flush_dcache_mft_record_page(ctx->ntfs_ino);
mark_mft_record_dirty(ctx->ntfs_ino);
done_unm:
ntfs_attr_put_search_ctx(ctx);
unmap_mft_record(base_ni);
/*
* Because resident attributes are handled by memcpy() to/from the
* corresponding MFT record, and because this form of i/o is byte
* aligned rather than block aligned, there is no need to bring the
* page uptodate here as in the non-resident case where we need to
* bring the buffers straddled by the write uptodate before
* generic_file_write() does the copying from userspace.
*
* We thus defer the uptodate bringing of the page region outside the
* region written to to ntfs_commit_write(), which makes the code
* simpler and saves one atomic kmap which is good.
*/
done:
ntfs_debug("Done.");
return 0;
err_out:
if (err == -ENOMEM)
ntfs_warning(vi->i_sb, "Error allocating memory required to "
"prepare the write.");
else {
ntfs_error(vi->i_sb, "Resident attribute prepare write failed "
"with error %i.", err);
NVolSetErrors(vol);
make_bad_inode(vi);
}
err_out2:
if (ctx)
ntfs_attr_put_search_ctx(ctx);
if (m)
unmap_mft_record(base_ni);
return err;
}
/**
* ntfs_commit_nonresident_write -
*
*/
static int ntfs_commit_nonresident_write(struct page *page,
unsigned from, unsigned to)
{
s64 pos = ((s64)page->index << PAGE_CACHE_SHIFT) + to;
struct inode *vi = page->mapping->host;
struct buffer_head *bh, *head;
unsigned int block_start, block_end, blocksize;
BOOL partial;
ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
"0x%lx, from = %u, to = %u.", vi->i_ino,
NTFS_I(vi)->type, page->index, from, to);
blocksize = 1 << vi->i_blkbits;
// FIXME: We need a whole slew of special cases in here for compressed
// files for example...
// For now, we know ntfs_prepare_write() would have failed so we can't
// get here in any of the cases which we have to special case, so we
// are just a ripped off, unrolled generic_commit_write().
bh = head = page_buffers(page);
block_start = 0;
partial = FALSE;
do {
block_end = block_start + blocksize;
if (block_end <= from || block_start >= to) {
if (!buffer_uptodate(bh))
partial = TRUE;
} else {
set_buffer_uptodate(bh);
mark_buffer_dirty(bh);
}
} while (block_start = block_end, (bh = bh->b_this_page) != head);
/*
* If this is a partial write which happened to make all buffers
* uptodate then we can optimize away a bogus ->readpage() for the next
* read(). Here we 'discover' whether the page went uptodate as a
* result of this (potentially partial) write.
*/
if (!partial)
SetPageUptodate(page);
/*
* Not convinced about this at all. See disparity comment above. For
* now we know ntfs_prepare_write() would have failed in the write
* exceeds i_size case, so this will never trigger which is fine.
*/
if (pos > i_size_read(vi)) {
ntfs_error(vi->i_sb, "Writing beyond the existing file size is "
"not supported yet. Sorry.");
return -EOPNOTSUPP;
// vi->i_size = pos;
// mark_inode_dirty(vi);
}
ntfs_debug("Done.");
return 0;
}
/**
* ntfs_commit_write - commit the received data
*
* This is called from generic_file_write() with i_sem held on the inode
* (@page->mapping->host). The @page is locked but not kmap()ped. The source
* data has already been copied into the @page. ntfs_prepare_write() has been
* called before the data copied and it returned success so we can take the
* results of various BUG checks and some error handling for granted.
*
* Need to mark modified blocks dirty so they get written out later when
* ntfs_writepage() is invoked by the VM.
*
* Return 0 on success or -errno on error.
*
* Should be using generic_commit_write(). This marks buffers uptodate and
* dirty, sets the page uptodate if all buffers in the page are uptodate, and
* updates i_size if the end of io is beyond i_size. In that case, it also
* marks the inode dirty.
*
* Cannot use generic_commit_write() due to ntfs specialities but can look at
* it for implementation guidance.
*
* If things have gone as outlined in ntfs_prepare_write(), then we do not
* need to do any page content modifications here at all, except in the write
* to resident attribute case, where we need to do the uptodate bringing here
* which we combine with the copying into the mft record which means we save
* one atomic kmap.
*/
static int ntfs_commit_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
struct inode *vi = page->mapping->host;
ntfs_inode *base_ni, *ni = NTFS_I(vi);
char *kaddr, *kattr;
ntfs_attr_search_ctx *ctx;
MFT_RECORD *m;
ATTR_RECORD *a;
u32 attr_len;
int err;
ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
"0x%lx, from = %u, to = %u.", vi->i_ino, ni->type,
page->index, from, to);
/* If the attribute is not resident, deal with it elsewhere. */
if (NInoNonResident(ni)) {
/* Only unnamed $DATA attributes can be compressed/encrypted. */
if (ni->type == AT_DATA && !ni->name_len) {
/* Encrypted files need separate handling. */
if (NInoEncrypted(ni)) {
// We never get here at present!
BUG();
}
/* Compressed data streams are handled in compress.c. */
if (NInoCompressed(ni)) {
// TODO: Implement this!
// return ntfs_write_compressed_block(page);
// We never get here at present!
BUG();
}
}
/* Normal data stream. */
return ntfs_commit_nonresident_write(page, from, to);
}
/*
* Attribute is resident, implying it is not compressed, encrypted, or
* sparse.
*/
if (!NInoAttr(ni))
base_ni = ni;
else
base_ni = ni->ext.base_ntfs_ino;
/* Map, pin, and lock the mft record. */
m = map_mft_record(base_ni);
if (IS_ERR(m)) {
err = PTR_ERR(m);
m = NULL;
ctx = NULL;
goto err_out;
}
ctx = ntfs_attr_get_search_ctx(base_ni, m);
if (unlikely(!ctx)) {
err = -ENOMEM;
goto err_out;
}
err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
CASE_SENSITIVE, 0, NULL, 0, ctx);
if (unlikely(err)) {
if (err == -ENOENT)
err = -EIO;
goto err_out;
}
a = ctx->attr;
/* The total length of the attribute value. */
attr_len = le32_to_cpu(a->data.resident.value_length);
BUG_ON(from > attr_len);
kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
kaddr = kmap_atomic(page, KM_USER0);
/* Copy the received data from the page to the mft record. */
memcpy(kattr + from, kaddr + from, to - from);
/* Update the attribute length if necessary. */
if (to > attr_len) {
attr_len = to;
a->data.resident.value_length = cpu_to_le32(attr_len);
}
/*
* If the page is not uptodate, bring the out of bounds area(s)
* uptodate by copying data from the mft record to the page.
*/
if (!PageUptodate(page)) {
if (from > 0)
memcpy(kaddr, kattr, from);
if (to < attr_len)
memcpy(kaddr + to, kattr + to, attr_len - to);
/* Zero the region outside the end of the attribute value. */
if (attr_len < PAGE_CACHE_SIZE)
memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
/*
* The probability of not having done any of the above is
* extremely small, so we just flush unconditionally.
*/
flush_dcache_page(page);
SetPageUptodate(page);
}
kunmap_atomic(kaddr, KM_USER0);
/* Update i_size if necessary. */
if (i_size_read(vi) < attr_len) {
unsigned long flags;
write_lock_irqsave(&ni->size_lock, flags);
ni->allocated_size = ni->initialized_size = attr_len;
i_size_write(vi, attr_len);
write_unlock_irqrestore(&ni->size_lock, flags);
}
/* Mark the mft record dirty, so it gets written back. */
flush_dcache_mft_record_page(ctx->ntfs_ino);
mark_mft_record_dirty(ctx->ntfs_ino);
ntfs_attr_put_search_ctx(ctx);
unmap_mft_record(base_ni);
ntfs_debug("Done.");
return 0;
err_out:
if (err == -ENOMEM) {
ntfs_warning(vi->i_sb, "Error allocating memory required to "
"commit the write.");
if (PageUptodate(page)) {
ntfs_warning(vi->i_sb, "Page is uptodate, setting "
"dirty so the write will be retried "
"later on by the VM.");
/*
* Put the page on mapping->dirty_pages, but leave its
* buffers' dirty state as-is.
*/
__set_page_dirty_nobuffers(page);
err = 0;
} else
ntfs_error(vi->i_sb, "Page is not uptodate. Written "
"data has been lost.");
} else {
ntfs_error(vi->i_sb, "Resident attribute commit write failed "
"with error %i.", err);
NVolSetErrors(ni->vol);
make_bad_inode(vi);
}
if (ctx)
ntfs_attr_put_search_ctx(ctx);
if (m)
unmap_mft_record(base_ni);
return err;
}
#endif /* NTFS_RW */
/**
* ntfs_aops - general address space operations for inodes and attributes
*/
struct address_space_operations ntfs_aops = {
.readpage = ntfs_readpage, /* Fill page with data. */
.sync_page = block_sync_page, /* Currently, just unplugs the
disk request queue. */
#ifdef NTFS_RW
.writepage = ntfs_writepage, /* Write dirty page to disk. */
.prepare_write = ntfs_prepare_write, /* Prepare page and buffers
ready to receive data. */
.commit_write = ntfs_commit_write, /* Commit received data. */
#endif /* NTFS_RW */
};
/**
* ntfs_mst_aops - general address space operations for mst protecteed inodes
* and attributes
*/
struct address_space_operations ntfs_mst_aops = {
.readpage = ntfs_readpage, /* Fill page with data. */
.sync_page = block_sync_page, /* Currently, just unplugs the
disk request queue. */
#ifdef NTFS_RW
.writepage = ntfs_writepage, /* Write dirty page to disk. */
.set_page_dirty = __set_page_dirty_nobuffers, /* Set the page dirty
without touching the buffers
belonging to the page. */
#endif /* NTFS_RW */
};
#ifdef NTFS_RW
/**
* mark_ntfs_record_dirty - mark an ntfs record dirty
* @page: page containing the ntfs record to mark dirty
* @ofs: byte offset within @page at which the ntfs record begins
*
* Set the buffers and the page in which the ntfs record is located dirty.
*
* The latter also marks the vfs inode the ntfs record belongs to dirty
* (I_DIRTY_PAGES only).
*
* If the page does not have buffers, we create them and set them uptodate.
* The page may not be locked which is why we need to handle the buffers under
* the mapping->private_lock. Once the buffers are marked dirty we no longer
* need the lock since try_to_free_buffers() does not free dirty buffers.
*/
void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs) {
struct address_space *mapping = page->mapping;
ntfs_inode *ni = NTFS_I(mapping->host);
struct buffer_head *bh, *head, *buffers_to_free = NULL;
unsigned int end, bh_size, bh_ofs;
BUG_ON(!PageUptodate(page));
end = ofs + ni->itype.index.block_size;
bh_size = 1 << VFS_I(ni)->i_blkbits;
spin_lock(&mapping->private_lock);
if (unlikely(!page_has_buffers(page))) {
spin_unlock(&mapping->private_lock);
bh = head = alloc_page_buffers(page, bh_size, 1);
spin_lock(&mapping->private_lock);
if (likely(!page_has_buffers(page))) {
struct buffer_head *tail;
do {
set_buffer_uptodate(bh);
tail = bh;
bh = bh->b_this_page;
} while (bh);
tail->b_this_page = head;
attach_page_buffers(page, head);
} else
buffers_to_free = bh;
}
bh = head = page_buffers(page);
do {
bh_ofs = bh_offset(bh);
if (bh_ofs + bh_size <= ofs)
continue;
if (unlikely(bh_ofs >= end))
break;
set_buffer_dirty(bh);
} while ((bh = bh->b_this_page) != head);
spin_unlock(&mapping->private_lock);
__set_page_dirty_nobuffers(page);
if (unlikely(buffers_to_free)) {
do {
bh = buffers_to_free->b_this_page;
free_buffer_head(buffers_to_free);
buffers_to_free = bh;
} while (buffers_to_free);
}
}
#endif /* NTFS_RW */
