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file.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* file.c - NTFS kernel file operations. Part of the Linux-NTFS project.
*
* Copyright (c) 2001-2015 Anton Altaparmakov and Tuxera Inc.
*/
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/buffer_head.h>
#include <linux/gfp.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/sched/signal.h>
#include <linux/swap.h>
#include <linux/uio.h>
#include <linux/writeback.h>
#include <asm/page.h>
#include <linux/uaccess.h>
#include "attrib.h"
#include "bitmap.h"
#include "inode.h"
#include "debug.h"
#include "lcnalloc.h"
#include "malloc.h"
#include "mft.h"
#include "ntfs.h"
/**
* ntfs_file_open - called when an inode is about to be opened
* @vi: inode to be opened
* @filp: file structure describing the inode
*
* Limit file size to the page cache limit on architectures where unsigned long
* is 32-bits. This is the most we can do for now without overflowing the page
* cache page index. Doing it this way means we don't run into problems because
* of existing too large files. It would be better to allow the user to read
* the beginning of the file but I doubt very much anyone is going to hit this
* check on a 32-bit architecture, so there is no point in adding the extra
* complexity required to support this.
*
* On 64-bit architectures, the check is hopefully optimized away by the
* compiler.
*
* After the check passes, just call generic_file_open() to do its work.
*/
static int ntfs_file_open(struct inode *vi, struct file *filp)
{
if (sizeof(unsigned long) < 8) {
if (i_size_read(vi) > MAX_LFS_FILESIZE)
return -EOVERFLOW;
}
return generic_file_open(vi, filp);
}
#ifdef NTFS_RW
/**
* ntfs_attr_extend_initialized - extend the initialized size of an attribute
* @ni: ntfs inode of the attribute to extend
* @new_init_size: requested new initialized size in bytes
*
* Extend the initialized size of an attribute described by the ntfs inode @ni
* to @new_init_size bytes. This involves zeroing any non-sparse space between
* the old initialized size and @new_init_size both in the page cache and on
* disk (if relevant complete pages are already uptodate in the page cache then
* these are simply marked dirty).
*
* As a side-effect, the file size (vfs inode->i_size) may be incremented as,
* in the resident attribute case, it is tied to the initialized size and, in
* the non-resident attribute case, it may not fall below the initialized size.
*
* Note that if the attribute is resident, we do not need to touch the page
* cache at all. This is because if the page cache page is not uptodate we
* bring it uptodate later, when doing the write to the mft record since we
* then already have the page mapped. And if the page is uptodate, the
* non-initialized region will already have been zeroed when the page was
* brought uptodate and the region may in fact already have been overwritten
* with new data via mmap() based writes, so we cannot just zero it. And since
* POSIX specifies that the behaviour of resizing a file whilst it is mmap()ped
* is unspecified, we choose not to do zeroing and thus we do not need to touch
* the page at all. For a more detailed explanation see ntfs_truncate() in
* fs/ntfs/inode.c.
*
* Return 0 on success and -errno on error. In the case that an error is
* encountered it is possible that the initialized size will already have been
* incremented some way towards @new_init_size but it is guaranteed that if
* this is the case, the necessary zeroing will also have happened and that all
* metadata is self-consistent.
*
* Locking: i_mutex on the vfs inode corrseponsind to the ntfs inode @ni must be
* held by the caller.
*/
static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size)
{
s64 old_init_size;
loff_t old_i_size;
pgoff_t index, end_index;
unsigned long flags;
struct inode *vi = VFS_I(ni);
ntfs_inode *base_ni;
MFT_RECORD *m = NULL;
ATTR_RECORD *a;
ntfs_attr_search_ctx *ctx = NULL;
struct address_space *mapping;
struct page *page = NULL;
u8 *kattr;
int err;
u32 attr_len;
read_lock_irqsave(&ni->size_lock, flags);
old_init_size = ni->initialized_size;
old_i_size = i_size_read(vi);
BUG_ON(new_init_size > ni->allocated_size);
read_unlock_irqrestore(&ni->size_lock, flags);
ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
"old_initialized_size 0x%llx, "
"new_initialized_size 0x%llx, i_size 0x%llx.",
vi->i_ino, (unsigned)le32_to_cpu(ni->type),
(unsigned long long)old_init_size,
(unsigned long long)new_init_size, old_i_size);
if (!NInoAttr(ni))
base_ni = ni;
else
base_ni = ni->ext.base_ntfs_ino;
/* Use goto to reduce indentation and we need the label below anyway. */
if (NInoNonResident(ni))
goto do_non_resident_extend;
BUG_ON(old_init_size != old_i_size);
m = map_mft_record(base_ni);
if (IS_ERR(m)) {
err = PTR_ERR(m);
m = 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;
BUG_ON(a->non_resident);
/* The total length of the attribute value. */
attr_len = le32_to_cpu(a->data.resident.value_length);
BUG_ON(old_i_size != (loff_t)attr_len);
/*
* Do the zeroing in the mft record and update the attribute size in
* the mft record.
*/
kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
memset(kattr + attr_len, 0, new_init_size - attr_len);
a->data.resident.value_length = cpu_to_le32((u32)new_init_size);
/* Finally, update the sizes in the vfs and ntfs inodes. */
write_lock_irqsave(&ni->size_lock, flags);
i_size_write(vi, new_init_size);
ni->initialized_size = new_init_size;
write_unlock_irqrestore(&ni->size_lock, flags);
goto done;
do_non_resident_extend:
/*
* If the new initialized size @new_init_size exceeds the current file
* size (vfs inode->i_size), we need to extend the file size to the
* new initialized size.
*/
if (new_init_size > old_i_size) {
m = map_mft_record(base_ni);
if (IS_ERR(m)) {
err = PTR_ERR(m);
m = 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;
BUG_ON(!a->non_resident);
BUG_ON(old_i_size != (loff_t)
sle64_to_cpu(a->data.non_resident.data_size));
a->data.non_resident.data_size = cpu_to_sle64(new_init_size);
flush_dcache_mft_record_page(ctx->ntfs_ino);
mark_mft_record_dirty(ctx->ntfs_ino);
/* Update the file size in the vfs inode. */
i_size_write(vi, new_init_size);
ntfs_attr_put_search_ctx(ctx);
ctx = NULL;
unmap_mft_record(base_ni);
m = NULL;
}
mapping = vi->i_mapping;
index = old_init_size >> PAGE_SHIFT;
end_index = (new_init_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
do {
/*
* Read the page. If the page is not present, this will zero
* the uninitialized regions for us.
*/
page = read_mapping_page(mapping, index, NULL);
if (IS_ERR(page)) {
err = PTR_ERR(page);
goto init_err_out;
}
/*
* Update the initialized size in the ntfs inode. This is
* enough to make ntfs_writepage() work.
*/
write_lock_irqsave(&ni->size_lock, flags);
ni->initialized_size = (s64)(index + 1) << PAGE_SHIFT;
if (ni->initialized_size > new_init_size)
ni->initialized_size = new_init_size;
write_unlock_irqrestore(&ni->size_lock, flags);
/* Set the page dirty so it gets written out. */
set_page_dirty(page);
put_page(page);
/*
* Play nice with the vm and the rest of the system. This is
* very much needed as we can potentially be modifying the
* initialised size from a very small value to a really huge
* value, e.g.
* f = open(somefile, O_TRUNC);
* truncate(f, 10GiB);
* seek(f, 10GiB);
* write(f, 1);
* And this would mean we would be marking dirty hundreds of
* thousands of pages or as in the above example more than
* two and a half million pages!
*
* TODO: For sparse pages could optimize this workload by using
* the FsMisc / MiscFs page bit as a "PageIsSparse" bit. This
* would be set in read_folio for sparse pages and here we would
* not need to mark dirty any pages which have this bit set.
* The only caveat is that we have to clear the bit everywhere
* where we allocate any clusters that lie in the page or that
* contain the page.
*
* TODO: An even greater optimization would be for us to only
* call read_folio() on pages which are not in sparse regions as
* determined from the runlist. This would greatly reduce the
* number of pages we read and make dirty in the case of sparse
* files.
*/
balance_dirty_pages_ratelimited(mapping);
cond_resched();
} while (++index < end_index);
read_lock_irqsave(&ni->size_lock, flags);
BUG_ON(ni->initialized_size != new_init_size);
read_unlock_irqrestore(&ni->size_lock, flags);
/* Now bring in sync the initialized_size in the mft record. */
m = map_mft_record(base_ni);
if (IS_ERR(m)) {
err = PTR_ERR(m);
m = NULL;
goto init_err_out;
}
ctx = ntfs_attr_get_search_ctx(base_ni, m);
if (unlikely(!ctx)) {
err = -ENOMEM;
goto init_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 init_err_out;
}
m = ctx->mrec;
a = ctx->attr;
BUG_ON(!a->non_resident);
a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
done:
flush_dcache_mft_record_page(ctx->ntfs_ino);
mark_mft_record_dirty(ctx->ntfs_ino);
if (ctx)
ntfs_attr_put_search_ctx(ctx);
if (m)
unmap_mft_record(base_ni);
ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
(unsigned long long)new_init_size, i_size_read(vi));
return 0;
init_err_out:
write_lock_irqsave(&ni->size_lock, flags);
ni->initialized_size = old_init_size;
write_unlock_irqrestore(&ni->size_lock, flags);
err_out:
if (ctx)
ntfs_attr_put_search_ctx(ctx);
if (m)
unmap_mft_record(base_ni);
ntfs_debug("Failed. Returning error code %i.", err);
return err;
}
static ssize_t ntfs_prepare_file_for_write(struct kiocb *iocb,
struct iov_iter *from)
{
loff_t pos;
s64 end, ll;
ssize_t err;
unsigned long flags;
struct file *file = iocb->ki_filp;
struct inode *vi = file_inode(file);
ntfs_inode *ni = NTFS_I(vi);
ntfs_volume *vol = ni->vol;
ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
"0x%llx, count 0x%zx.", vi->i_ino,
(unsigned)le32_to_cpu(ni->type),
(unsigned long long)iocb->ki_pos,
iov_iter_count(from));
err = generic_write_checks(iocb, from);
if (unlikely(err <= 0))
goto out;
/*
* All checks have passed. Before we start doing any writing we want
* to abort any totally illegal writes.
*/
BUG_ON(NInoMstProtected(ni));
BUG_ON(ni->type != AT_DATA);
/* If file is encrypted, deny access, just like NT4. */
if (NInoEncrypted(ni)) {
/* Only $DATA attributes can be encrypted. */
/*
* Reminder for later: Encrypted files are _always_
* non-resident so that the content can always be encrypted.
*/
ntfs_debug("Denying write access to encrypted file.");
err = -EACCES;
goto out;
}
if (NInoCompressed(ni)) {
/* Only unnamed $DATA attribute can be compressed. */
BUG_ON(ni->name_len);
/*
* Reminder for later: If resident, the data is not actually
* compressed. Only on the switch to non-resident does
* compression kick in. This is in contrast to encrypted files
* (see above).
*/
ntfs_error(vi->i_sb, "Writing to compressed files is not "
"implemented yet. Sorry.");
err = -EOPNOTSUPP;
goto out;
}
err = file_remove_privs(file);
if (unlikely(err))
goto out;
/*
* Our ->update_time method always succeeds thus file_update_time()
* cannot fail either so there is no need to check the return code.
*/
file_update_time(file);
pos = iocb->ki_pos;
/* The first byte after the last cluster being written to. */
end = (pos + iov_iter_count(from) + vol->cluster_size_mask) &
~(u64)vol->cluster_size_mask;
/*
* If the write goes beyond the allocated size, extend the allocation
* to cover the whole of the write, rounded up to the nearest cluster.
*/
read_lock_irqsave(&ni->size_lock, flags);
ll = ni->allocated_size;
read_unlock_irqrestore(&ni->size_lock, flags);
if (end > ll) {
/*
* Extend the allocation without changing the data size.
*
* Note we ensure the allocation is big enough to at least
* write some data but we do not require the allocation to be
* complete, i.e. it may be partial.
*/
ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
if (likely(ll >= 0)) {
BUG_ON(pos >= ll);
/* If the extension was partial truncate the write. */
if (end > ll) {
ntfs_debug("Truncating write to inode 0x%lx, "
"attribute type 0x%x, because "
"the allocation was only "
"partially extended.",
vi->i_ino, (unsigned)
le32_to_cpu(ni->type));
iov_iter_truncate(from, ll - pos);
}
} else {
err = ll;
read_lock_irqsave(&ni->size_lock, flags);
ll = ni->allocated_size;
read_unlock_irqrestore(&ni->size_lock, flags);
/* Perform a partial write if possible or fail. */
if (pos < ll) {
ntfs_debug("Truncating write to inode 0x%lx "
"attribute type 0x%x, because "
"extending the allocation "
"failed (error %d).",
vi->i_ino, (unsigned)
le32_to_cpu(ni->type),
(int)-err);
iov_iter_truncate(from, ll - pos);
} else {
if (err != -ENOSPC)
ntfs_error(vi->i_sb, "Cannot perform "
"write to inode "
"0x%lx, attribute "
"type 0x%x, because "
"extending the "
"allocation failed "
"(error %ld).",
vi->i_ino, (unsigned)
le32_to_cpu(ni->type),
(long)-err);
else
ntfs_debug("Cannot perform write to "
"inode 0x%lx, "
"attribute type 0x%x, "
"because there is not "
"space left.",
vi->i_ino, (unsigned)
le32_to_cpu(ni->type));
goto out;
}
}
}
/*
* If the write starts beyond the initialized size, extend it up to the
* beginning of the write and initialize all non-sparse space between
* the old initialized size and the new one. This automatically also
* increments the vfs inode->i_size to keep it above or equal to the
* initialized_size.
*/
read_lock_irqsave(&ni->size_lock, flags);
ll = ni->initialized_size;
read_unlock_irqrestore(&ni->size_lock, flags);
if (pos > ll) {
/*
* Wait for ongoing direct i/o to complete before proceeding.
* New direct i/o cannot start as we hold i_mutex.
*/
inode_dio_wait(vi);
err = ntfs_attr_extend_initialized(ni, pos);
if (unlikely(err < 0))
ntfs_error(vi->i_sb, "Cannot perform write to inode "
"0x%lx, attribute type 0x%x, because "
"extending the initialized size "
"failed (error %d).", vi->i_ino,
(unsigned)le32_to_cpu(ni->type),
(int)-err);
}
out:
return err;
}
/**
* __ntfs_grab_cache_pages - obtain a number of locked pages
* @mapping: address space mapping from which to obtain page cache pages
* @index: starting index in @mapping at which to begin obtaining pages
* @nr_pages: number of page cache pages to obtain
* @pages: array of pages in which to return the obtained page cache pages
* @cached_page: allocated but as yet unused page
*
* Obtain @nr_pages locked page cache pages from the mapping @mapping and
* starting at index @index.
*
* If a page is newly created, add it to lru list
*
* Note, the page locks are obtained in ascending page index order.
*/
static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
pgoff_t index, const unsigned nr_pages, struct page **pages,
struct page **cached_page)
{
int err, nr;
BUG_ON(!nr_pages);
err = nr = 0;
do {
pages[nr] = find_get_page_flags(mapping, index, FGP_LOCK |
FGP_ACCESSED);
if (!pages[nr]) {
if (!*cached_page) {
*cached_page = page_cache_alloc(mapping);
if (unlikely(!*cached_page)) {
err = -ENOMEM;
goto err_out;
}
}
err = add_to_page_cache_lru(*cached_page, mapping,
index,
mapping_gfp_constraint(mapping, GFP_KERNEL));
if (unlikely(err)) {
if (err == -EEXIST)
continue;
goto err_out;
}
pages[nr] = *cached_page;
*cached_page = NULL;
}
index++;
nr++;
} while (nr < nr_pages);
out:
return err;
err_out:
while (nr > 0) {
unlock_page(pages[--nr]);
put_page(pages[nr]);
}
goto out;
}
static inline void ntfs_submit_bh_for_read(struct buffer_head *bh)
{
lock_buffer(bh);
get_bh(bh);
bh->b_end_io = end_buffer_read_sync;
submit_bh(REQ_OP_READ, bh);
}
/**
* ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
* @pages: array of destination pages
* @nr_pages: number of pages in @pages
* @pos: byte position in file at which the write begins
* @bytes: number of bytes to be written
*
* This is called for non-resident attributes from ntfs_file_buffered_write()
* with i_mutex held on the inode (@pages[0]->mapping->host). There are
* @nr_pages pages in @pages which are locked but not kmap()ped. The source
* data has not yet been copied into the @pages.
*
* Need to fill any holes with actual clusters, allocate buffers if necessary,
* ensure all the buffers are mapped, and bring uptodate any buffers that are
* only partially being written to.
*
* If @nr_pages is greater than one, we are guaranteed that the cluster size is
* greater than PAGE_SIZE, that all pages in @pages are entirely inside
* the same cluster and that they are the entirety of that cluster, and that
* the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
*
* i_size is not to be modified yet.
*
* Return 0 on success or -errno on error.
*/
static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
unsigned nr_pages, s64 pos, size_t bytes)
{
VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
LCN lcn;
s64 bh_pos, vcn_len, end, initialized_size;
sector_t lcn_block;
struct page *page;
struct inode *vi;
ntfs_inode *ni, *base_ni = NULL;
ntfs_volume *vol;
runlist_element *rl, *rl2;
struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
ntfs_attr_search_ctx *ctx = NULL;
MFT_RECORD *m = NULL;
ATTR_RECORD *a = NULL;
unsigned long flags;
u32 attr_rec_len = 0;
unsigned blocksize, u;
int err, mp_size;
bool rl_write_locked, was_hole, is_retry;
unsigned char blocksize_bits;
struct {
u8 runlist_merged:1;
u8 mft_attr_mapped:1;
u8 mp_rebuilt:1;
u8 attr_switched:1;
} status = { 0, 0, 0, 0 };
BUG_ON(!nr_pages);
BUG_ON(!pages);
BUG_ON(!*pages);
vi = pages[0]->mapping->host;
ni = NTFS_I(vi);
vol = ni->vol;
ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
"index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
vi->i_ino, ni->type, pages[0]->index, nr_pages,
(long long)pos, bytes);
blocksize = vol->sb->s_blocksize;
blocksize_bits = vol->sb->s_blocksize_bits;
u = 0;
do {
page = pages[u];
BUG_ON(!page);
/*
* 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);
if (unlikely(!page_has_buffers(page)))
return -ENOMEM;
}
} while (++u < nr_pages);
rl_write_locked = false;
rl = NULL;
err = 0;
vcn = lcn = -1;
vcn_len = 0;
lcn_block = -1;
was_hole = false;
cpos = pos >> vol->cluster_size_bits;
end = pos + bytes;
cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
/*
* Loop over each page and for each page over each buffer. Use goto to
* reduce indentation.
*/
u = 0;
do_next_page:
page = pages[u];
bh_pos = (s64)page->index << PAGE_SHIFT;
bh = head = page_buffers(page);
do {
VCN cdelta;
s64 bh_end;
unsigned bh_cofs;
/* Clear buffer_new on all buffers to reinitialise state. */
if (buffer_new(bh))
clear_buffer_new(bh);
bh_end = bh_pos + blocksize;
bh_cpos = bh_pos >> vol->cluster_size_bits;
bh_cofs = bh_pos & vol->cluster_size_mask;
if (buffer_mapped(bh)) {
/*
* The buffer is already mapped. If it is uptodate,
* ignore it.
*/
if (buffer_uptodate(bh))
continue;
/*
* The buffer is not uptodate. If the page is uptodate
* set the buffer uptodate and otherwise ignore it.
*/
if (PageUptodate(page)) {
set_buffer_uptodate(bh);
continue;
}
/*
* Neither the page nor the buffer are uptodate. If
* the buffer is only partially being written to, we
* need to read it in before the write, i.e. now.
*/
if ((bh_pos < pos && bh_end > pos) ||
(bh_pos < end && bh_end > end)) {
/*
* If the buffer is fully or partially within
* the initialized size, do an actual read.
* Otherwise, simply zero the buffer.
*/
read_lock_irqsave(&ni->size_lock, flags);
initialized_size = ni->initialized_size;
read_unlock_irqrestore(&ni->size_lock, flags);
if (bh_pos < initialized_size) {
ntfs_submit_bh_for_read(bh);
*wait_bh++ = bh;
} else {
zero_user(page, bh_offset(bh),
blocksize);
set_buffer_uptodate(bh);
}
}
continue;
}
/* Unmapped buffer. Need to map it. */
bh->b_bdev = vol->sb->s_bdev;
/*
* If the current buffer is in the same clusters as the map
* cache, there is no need to check the runlist again. The
* map cache is made up of @vcn, which is the first cached file
* cluster, @vcn_len which is the number of cached file
* clusters, @lcn is the device cluster corresponding to @vcn,
* and @lcn_block is the block number corresponding to @lcn.
*/
cdelta = bh_cpos - vcn;
if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
map_buffer_cached:
BUG_ON(lcn < 0);
bh->b_blocknr = lcn_block +
(cdelta << (vol->cluster_size_bits -
blocksize_bits)) +
(bh_cofs >> blocksize_bits);
set_buffer_mapped(bh);
/*
* If the page is uptodate so is the buffer. If the
* buffer is fully outside the write, we ignore it if
* it was already allocated and we mark it dirty so it
* gets written out if we allocated it. On the other
* hand, if we allocated the buffer but we are not
* marking it dirty we set buffer_new so we can do
* error recovery.
*/
if (PageUptodate(page)) {
if (!buffer_uptodate(bh))
set_buffer_uptodate(bh);
if (unlikely(was_hole)) {
/* We allocated the buffer. */
clean_bdev_bh_alias(bh);
if (bh_end <= pos || bh_pos >= end)
mark_buffer_dirty(bh);
else
set_buffer_new(bh);
}
continue;
}
/* Page is _not_ uptodate. */
if (likely(!was_hole)) {
/*
* Buffer was already allocated. If it is not
* uptodate and is only partially being written
* to, we need to read it in before the write,
* i.e. now.
*/
if (!buffer_uptodate(bh) && bh_pos < end &&
bh_end > pos &&
(bh_pos < pos ||
bh_end > end)) {
/*
* If the buffer is fully or partially
* within the initialized size, do an
* actual read. Otherwise, simply zero
* the buffer.
*/
read_lock_irqsave(&ni->size_lock,
flags);
initialized_size = ni->initialized_size;
read_unlock_irqrestore(&ni->size_lock,
flags);
if (bh_pos < initialized_size) {
ntfs_submit_bh_for_read(bh);
*wait_bh++ = bh;
} else {
zero_user(page, bh_offset(bh),
blocksize);
set_buffer_uptodate(bh);
}
}
continue;
}
/* We allocated the buffer. */
clean_bdev_bh_alias(bh);
/*
* If the buffer is fully outside the write, zero it,
* set it uptodate, and mark it dirty so it gets
* written out. If it is partially being written to,
* zero region surrounding the write but leave it to
* commit write to do anything else. Finally, if the
* buffer is fully being overwritten, do nothing.
*/
if (bh_end <= pos || bh_pos >= end) {
if (!buffer_uptodate(bh)) {
zero_user(page, bh_offset(bh),
blocksize);
set_buffer_uptodate(bh);
}
mark_buffer_dirty(bh);
continue;
}
set_buffer_new(bh);
if (!buffer_uptodate(bh) &&
(bh_pos < pos || bh_end > end)) {
u8 *kaddr;
unsigned pofs;
kaddr = kmap_atomic(page);
if (bh_pos < pos) {
pofs = bh_pos & ~PAGE_MASK;
memset(kaddr + pofs, 0, pos - bh_pos);
}
if (bh_end > end) {
pofs = end & ~PAGE_MASK;
memset(kaddr + pofs, 0, bh_end - end);
}
kunmap_atomic(kaddr);
flush_dcache_page(page);
}
continue;
}
/*
* Slow path: this is the first buffer in the cluster. If it
* is outside allocated size and is not uptodate, zero it and
* set it uptodate.
*/
read_lock_irqsave(&ni->size_lock, flags);
initialized_size = ni->allocated_size;
read_unlock_irqrestore(&ni->size_lock, flags);
if (bh_pos > initialized_size) {
if (PageUptodate(page)) {
if (!buffer_uptodate(bh))
set_buffer_uptodate(bh);
} else if (!buffer_uptodate(bh)) {
zero_user(page, bh_offset(bh), blocksize);
set_buffer_uptodate(bh);
}
continue;
}
is_retry = false;
if (!rl) {
down_read(&ni->runlist.lock);
retry_remap:
rl = ni->runlist.rl;
}
if (likely(rl != NULL)) {
/* Seek to element containing target cluster. */
while (rl->length && rl[1].vcn <= bh_cpos)
rl++;
lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
if (likely(lcn >= 0)) {
/*
* Successful remap, setup the map cache and
* use that to deal with the buffer.
*/
was_hole = false;
vcn = bh_cpos;
vcn_len = rl[1].vcn - vcn;
lcn_block = lcn << (vol->cluster_size_bits -
blocksize_bits);
cdelta = 0;
/*
* If the number of remaining clusters touched
* by the write is smaller or equal to the
* number of cached clusters, unlock the
* runlist as the map cache will be used from
* now on.
*/
if (likely(vcn + vcn_len >= cend)) {
if (rl_write_locked) {
up_write(&ni->runlist.lock);
rl_write_locked = false;
} else
up_read(&ni->runlist.lock);
rl = NULL;
}
goto map_buffer_cached;
}
} else
lcn = LCN_RL_NOT_MAPPED;
/*
* If it is not a hole and not out of bounds, the runlist is
* probably unmapped so try to map it now.
*/
if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
/* Attempt to map runlist. */
if (!rl_write_locked) {
/*
* We need the runlist locked for
* writing, so if it is locked for
* reading relock it now and retry in
* case it changed whilst we dropped
* the lock.
*/
up_read(&ni->runlist.lock);
down_write(&ni->runlist.lock);
rl_write_locked = true;
goto retry_remap;
}
err = ntfs_map_runlist_nolock(ni, bh_cpos,
NULL);
if (likely(!err)) {
is_retry = true;
goto retry_remap;
}
/*
* If @vcn is out of bounds, pretend @lcn is
* LCN_ENOENT. As long as the buffer is out
* of bounds this will work fine.
*/
if (err == -ENOENT) {
lcn = LCN_ENOENT;
err = 0;
goto rl_not_mapped_enoent;
}
} else
err = -EIO;
/* 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, "
"vcn offset 0x%x, because its "
"location on disk could not be "
"determined%s (error code %i).",
ni->mft_no, ni->type,
(unsigned long long)bh_cpos,
(unsigned)bh_pos &
vol->cluster_size_mask,
is_retry ? " even after retrying" : "",
err);
break;
}
rl_not_mapped_enoent:
/*
* The buffer is in a hole or out of bounds. We need to fill
* the hole, unless the buffer is in a cluster which is not
* touched by the write, in which case we just leave the buffer
* unmapped. This can only happen when the cluster size is
* less than the page cache size.
*/
if (unlikely(vol->cluster_size < PAGE_SIZE)) {
bh_cend = (bh_end + vol->cluster_size - 1) >>
vol->cluster_size_bits;
if ((bh_cend <= cpos || bh_cpos >= cend)) {
bh->b_blocknr = -1;
/*
* If the buffer is uptodate we skip it. If it
* is not but the page is uptodate, we can set
* the buffer uptodate. If the page is not
* uptodate, we can clear the buffer and set it
* uptodate. Whether this is worthwhile is
* debatable and this could be removed.
*/
if (PageUptodate(page)) {
if (!buffer_uptodate(bh))
set_buffer_uptodate(bh);
} else if (!buffer_uptodate(bh)) {
zero_user(page, bh_offset(bh),
blocksize);
set_buffer_uptodate(bh);
}
continue;
}
}
/*
* Out of bounds buffer is invalid if it was not really out of
* bounds.
*/
BUG_ON(lcn != LCN_HOLE);
/*
* We need the runlist locked for writing, so if it is locked
* for reading relock it now and retry in case it changed
* whilst we dropped the lock.
*/
BUG_ON(!rl);
if (!rl_write_locked) {
up_read(&ni->runlist.lock);
down_write(&ni->runlist.lock);
rl_write_locked = true;
goto retry_remap;
}
/* Find the previous last allocated cluster. */
BUG_ON(rl->lcn != LCN_HOLE);
lcn = -1;
rl2 = rl;
while (--rl2 >= ni->runlist.rl) {
if (rl2->lcn >= 0) {
lcn = rl2->lcn + rl2->length;
break;
}
}
rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
false);
if (IS_ERR(rl2)) {
err = PTR_ERR(rl2);
ntfs_debug("Failed to allocate cluster, error code %i.",
err);
break;
}
lcn = rl2->lcn;
rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
if (IS_ERR(rl)) {
err = PTR_ERR(rl);
if (err != -ENOMEM)
err = -EIO;
if (ntfs_cluster_free_from_rl(vol, rl2)) {
ntfs_error(vol->sb, "Failed to release "
"allocated cluster in error "
"code path. Run chkdsk to "
"recover the lost cluster.");
NVolSetErrors(vol);
}
ntfs_free(rl2);
break;
}
ni->runlist.rl = rl;
status.runlist_merged = 1;
ntfs_debug("Allocated cluster, lcn 0x%llx.",