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-rw-r--r--kernel/fs/ntfs/aops.c1773
1 files changed, 1773 insertions, 0 deletions
diff --git a/kernel/fs/ntfs/aops.c b/kernel/fs/ntfs/aops.c
new file mode 100644
index 000000000..f0de4b6b8
--- /dev/null
+++ b/kernel/fs/ntfs/aops.c
@@ -0,0 +1,1773 @@
+/**
+ * aops.c - NTFS kernel address space operations and page cache handling.
+ *
+ * Copyright (c) 2001-2014 Anton Altaparmakov and Tuxera Inc.
+ * 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/fs.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/bit_spinlock.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)
+{
+ unsigned long flags;
+ struct buffer_head *first, *tmp;
+ struct page *page;
+ struct inode *vi;
+ ntfs_inode *ni;
+ int page_uptodate = 1;
+
+ page = bh->b_page;
+ vi = page->mapping->host;
+ ni = NTFS_I(vi);
+
+ if (likely(uptodate)) {
+ loff_t i_size;
+ s64 file_ofs, init_size;
+
+ set_buffer_uptodate(bh);
+
+ file_ofs = ((s64)page->index << PAGE_CACHE_SHIFT) +
+ bh_offset(bh);
+ read_lock_irqsave(&ni->size_lock, flags);
+ init_size = ni->initialized_size;
+ i_size = i_size_read(vi);
+ read_unlock_irqrestore(&ni->size_lock, flags);
+ if (unlikely(init_size > i_size)) {
+ /* Race with shrinking truncate. */
+ init_size = i_size;
+ }
+ /* Check for the current buffer head overflowing. */
+ if (unlikely(file_ofs + bh->b_size > init_size)) {
+ int ofs;
+ void *kaddr;
+
+ ofs = 0;
+ if (file_ofs < init_size)
+ ofs = init_size - file_ofs;
+ local_irq_save(flags);
+ kaddr = kmap_atomic(page);
+ memset(kaddr + bh_offset(bh) + ofs, 0,
+ bh->b_size - ofs);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr);
+ local_irq_restore(flags);
+ }
+ } else {
+ clear_buffer_uptodate(bh);
+ SetPageError(page);
+ ntfs_error(ni->vol->sb, "Buffer I/O error, logical block "
+ "0x%llx.", (unsigned long long)bh->b_blocknr);
+ }
+ first = page_buffers(page);
+ flags = bh_uptodate_lock_irqsave(first);
+ 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);
+ bh_uptodate_unlock_irqrestore(first, 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 {
+ u8 *kaddr;
+ 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);
+ local_irq_save_nort(flags);
+ kaddr = kmap_atomic(page);
+ for (i = 0; i < recs; i++)
+ post_read_mst_fixup((NTFS_RECORD*)(kaddr +
+ i * rec_size), rec_size);
+ kunmap_atomic(kaddr);
+ local_irq_restore_nort(flags);
+ flush_dcache_page(page);
+ if (likely(page_uptodate && !PageError(page)))
+ SetPageUptodate(page);
+ }
+ unlock_page(page);
+ return;
+still_busy:
+ bh_uptodate_unlock_irqrestore(first, flags);
+}
+
+/**
+ * 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)
+{
+ loff_t i_size;
+ VCN vcn;
+ LCN lcn;
+ s64 init_size;
+ struct inode *vi;
+ 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;
+
+ vi = page->mapping->host;
+ ni = NTFS_I(vi);
+ 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 = vol->sb->s_blocksize;
+ blocksize_bits = vol->sb->s_blocksize_bits;
+
+ if (!page_has_buffers(page)) {
+ create_empty_buffers(page, blocksize, 0);
+ if (unlikely(!page_has_buffers(page))) {
+ unlock_page(page);
+ return -ENOMEM;
+ }
+ }
+ bh = head = page_buffers(page);
+ BUG_ON(!bh);
+
+ /*
+ * We may be racing with truncate. To avoid some of the problems we
+ * now take a snapshot of the various sizes and use those for the whole
+ * of the function. In case of an extending truncate it just means we
+ * may leave some buffers unmapped which are now allocated. This is
+ * not a problem since these buffers will just get mapped when a write
+ * occurs. In case of a shrinking truncate, we will detect this later
+ * on due to the runlist being incomplete and if the page is being
+ * fully truncated, truncate will throw it away as soon as we unlock
+ * it so no need to worry what we do with it.
+ */
+ iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
+ read_lock_irqsave(&ni->size_lock, flags);
+ lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits;
+ init_size = ni->initialized_size;
+ i_size = i_size_read(vi);
+ read_unlock_irqrestore(&ni->size_lock, flags);
+ if (unlikely(init_size > i_size)) {
+ /* Race with shrinking truncate. */
+ init_size = i_size;
+ }
+ zblock = (init_size + blocksize - 1) >> blocksize_bits;
+
+ /* Loop through all the buffers in the page. */
+ rl = NULL;
+ nr = i = 0;
+ do {
+ int err = 0;
+
+ 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) {
+ 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;
+ } else if (!rl)
+ up_read(&ni->runlist.lock);
+ /*
+ * If buffer is outside the runlist, treat it as a
+ * hole. This can happen due to concurrent truncate
+ * for example.
+ */
+ if (err == -ENOENT || lcn == LCN_ENOENT) {
+ err = 0;
+ goto handle_hole;
+ }
+ /* Hard error, zero out region. */
+ if (!err)
+ err = -EIO;
+ 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 %i).", ni->mft_no,
+ ni->type, (unsigned long long)vcn,
+ vcn_ofs, is_retry ? " even after "
+ "retrying" : "", err);
+ }
+ /*
+ * 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:
+ zero_user(page, i * blocksize, blocksize);
+ if (likely(!err))
+ 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)
+{
+ loff_t i_size;
+ struct inode *vi;
+ ntfs_inode *ni, *base_ni;
+ u8 *addr;
+ ntfs_attr_search_ctx *ctx;
+ MFT_RECORD *mrec;
+ unsigned long flags;
+ u32 attr_len;
+ int err = 0;
+
+retry_readpage:
+ BUG_ON(!PageLocked(page));
+ vi = page->mapping->host;
+ 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)) {
+ zero_user(page, 0, PAGE_CACHE_SIZE);
+ ntfs_debug("Read outside i_size - truncated?");
+ goto done;
+ }
+ /*
+ * 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(vi);
+ /*
+ * Only $DATA attributes can be encrypted and only unnamed $DATA
+ * attributes can be compressed. Index root can have the flags set but
+ * this means to create compressed/encrypted files, not that the
+ * attribute is compressed/encrypted. Note we need to check for
+ * AT_INDEX_ALLOCATION since this is the type of both directory and
+ * index inodes.
+ */
+ if (ni->type != AT_INDEX_ALLOCATION) {
+ /* If attribute is encrypted, deny access, just like NT4. */
+ if (NInoEncrypted(ni)) {
+ BUG_ON(ni->type != AT_DATA);
+ err = -EACCES;
+ goto err_out;
+ }
+ /* Compressed data streams are handled in compress.c. */
+ if (NInoNonResident(ni) && NInoCompressed(ni)) {
+ BUG_ON(ni->type != AT_DATA);
+ BUG_ON(ni->name_len);
+ return ntfs_read_compressed_block(page);
+ }
+ }
+ /* NInoNonResident() == NInoIndexAllocPresent() */
+ if (NInoNonResident(ni)) {
+ /* Normal, non-resident 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. Note the attribute can actually be marked compressed
+ * but if it is resident the actual data is not compressed so we are
+ * ok to ignore the compressed flag here.
+ */
+ if (unlikely(page->index > 0)) {
+ zero_user(page, 0, PAGE_CACHE_SIZE);
+ 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;
+ }
+ /*
+ * If a parallel write made the attribute non-resident, drop the mft
+ * record and retry the readpage.
+ */
+ if (unlikely(NInoNonResident(ni))) {
+ unmap_mft_record(base_ni);
+ goto retry_readpage;
+ }
+ 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;
+ i_size = i_size_read(vi);
+ read_unlock_irqrestore(&ni->size_lock, flags);
+ if (unlikely(attr_len > i_size)) {
+ /* Race with shrinking truncate. */
+ attr_len = i_size;
+ }
+ addr = kmap_atomic(page);
+ /* Copy the data to the page. */
+ memcpy(addr, (u8*)ctx->attr +
+ le16_to_cpu(ctx->attr->data.resident.value_offset),
+ attr_len);
+ /* Zero the remainder of the page. */
+ memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
+ flush_dcache_page(page);
+ kunmap_atomic(addr);
+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 = vol->sb->s_blocksize;
+ blocksize_bits = vol->sb->s_blocksize_bits;
+ if (!page_has_buffers(page)) {
+ BUG_ON(!PageUptodate(page));
+ create_empty_buffers(page, blocksize,
+ (1 << BH_Uptodate) | (1 << BH_Dirty));
+ if (unlikely(!page_has_buffers(page))) {
+ 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 buffers' dirty state as-is.
+ */
+ redirty_page_for_writepage(wbc, page);
+ unlock_page(page);
+ return 0;
+ }
+ }
+ bh = head = page_buffers(page);
+ BUG_ON(!bh);
+
+ /* 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) {
+ u8 *kaddr;
+ unsigned long *bpos, *bend;
+
+ /* Check if the buffer is zero. */
+ kaddr = kmap_atomic(page);
+ bpos = (unsigned long *)(kaddr + bh_offset(bh));
+ bend = (unsigned long *)((u8*)bpos + blocksize);
+ do {
+ if (unlikely(*bpos))
+ break;
+ } while (likely(++bpos < bend));
+ kunmap_atomic(kaddr);
+ if (bpos == bend) {
+ /*
+ * Buffer is zero and sparse, no need to write
+ * it.
+ */
+ bh->b_blocknr = -1;
+ clear_buffer_dirty(bh);
+ continue;
+ }
+ // 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;
+ } else if (!rl)
+ up_read(&ni->runlist.lock);
+ /*
+ * If buffer is outside the runlist, truncate has cut it out
+ * of the runlist. Just clean and clear the buffer and set it
+ * uptodate so it can get discarded by the VM.
+ */
+ if (err == -ENOENT || lcn == LCN_ENOENT) {
+ bh->b_blocknr = -1;
+ clear_buffer_dirty(bh);
+ zero_user(page, bh_offset(bh), blocksize);
+ set_buffer_uptodate(bh);
+ err = 0;
+ continue;
+ }
+ /* Failed to map the buffer, even after retrying. */
+ if (!err)
+ err = -EIO;
+ 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 %i).", ni->mft_no,
+ ni->type, (unsigned long long)vcn,
+ vcn_ofs, is_retry ? " even after "
+ "retrying" : "", err);
+ 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() is not 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 {
+ 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. */
+
+ /* Submit the prepared buffers for i/o. */
+ 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;
+ }
+ bh = next;
+ } while (bh != head);
+ unlock_page(page);
+
+ /* 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 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;
+ struct buffer_head *bhs[MAX_BUF_PER_PAGE];
+ runlist_element *rl;
+ int i, nr_locked_nis, nr_recs, nr_bhs, max_bhs, bhs_per_rec, err, err2;
+ unsigned bh_size, rec_size_bits;
+ bool sync, is_mft, page_is_dirty, rec_is_dirty;
+ unsigned char bh_size_bits;
+
+ 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)));
+ bh_size = vol->sb->s_blocksize;
+ bh_size_bits = vol->sb->s_blocksize_bits;
+ max_bhs = PAGE_CACHE_SIZE / bh_size;
+ BUG_ON(!max_bhs);
+ BUG_ON(max_bhs > MAX_BUF_PER_PAGE);
+
+ /* Were we called for sync purposes? */
+ sync = (wbc->sync_mode == WB_SYNC_ALL);
+
+ /* Make sure we have mapped buffers. */
+ 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;
+
+ bh->b_bdev = vol->sb->s_bdev;
+ /* 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;
+ if (!rl)
+ up_read(&ni->runlist.lock);
+ }
+ /* 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).",
+ (long long)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 (!trylock_buffer(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. */
+ mutex_lock(&tni->extent_lock);
+ if (tni->nr_extents >= 0)
+ base_tni = tni;
+ else {
+ base_tni = tni->ext.base_ntfs_ino;
+ BUG_ON(!base_tni);
+ }
+ mutex_unlock(&tni->extent_lock);
+ ntfs_debug("Unlocking %s inode 0x%lx.",
+ tni == base_tni ? "base" : "extent",
+ tni->mft_no);
+ mutex_unlock(&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 *addr;
+ ntfs_attr_search_ctx *ctx = NULL;
+ MFT_RECORD *m = NULL;
+ u32 attr_len;
+ int err;
+
+retry_writepage:
+ 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, PAGE_CACHE_SIZE);
+ unlock_page(page);
+ ntfs_debug("Write outside i_size - truncated?");
+ return 0;
+ }
+ /*
+ * Only $DATA attributes can be encrypted and only unnamed $DATA
+ * attributes can be compressed. Index root can have the flags set but
+ * this means to create compressed/encrypted files, not that the
+ * attribute is compressed/encrypted. Note we need to check for
+ * AT_INDEX_ALLOCATION since this is the type of both directory and
+ * index inodes.
+ */
+ if (ni->type != AT_INDEX_ALLOCATION) {
+ /* If file is encrypted, deny access, just like NT4. */
+ if (NInoEncrypted(ni)) {
+ unlock_page(page);
+ BUG_ON(ni->type != AT_DATA);
+ ntfs_debug("Denying write access to encrypted file.");
+ return -EACCES;
+ }
+ /* Compressed data streams are handled in compress.c. */
+ if (NInoNonResident(ni) && NInoCompressed(ni)) {
+ BUG_ON(ni->type != AT_DATA);
+ BUG_ON(ni->name_len);
+ // TODO: Implement and replace this 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 (NInoNonResident(ni) && NInoSparse(ni)) {
+ unlock_page(page);
+ ntfs_error(vi->i_sb, "Writing to sparse files is not "
+ "supported yet. Sorry.");
+ return -EOPNOTSUPP;
+ }
+ }
+ /* NInoNonResident() == NInoIndexAllocPresent() */
+ if (NInoNonResident(ni)) {
+ /* 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;
+ zero_user_segment(page, ofs, PAGE_CACHE_SIZE);
+ }
+ /* Handle mst protected attributes. */
+ if (NInoMstProtected(ni))
+ return ntfs_write_mst_block(page, wbc);
+ /* Normal, non-resident data stream. */
+ return ntfs_write_block(page, wbc);
+ }
+ /*
+ * Attribute is resident, implying it is not compressed, encrypted, 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. Note the attribute can actually be
+ * marked compressed but if it is resident the actual data is not
+ * compressed so we are ok to ignore the compressed flag here.
+ */
+ 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;
+ }
+ /*
+ * If a parallel write made the attribute non-resident, drop the mft
+ * record and retry the writepage.
+ */
+ if (unlikely(NInoNonResident(ni))) {
+ unmap_mft_record(base_ni);
+ goto retry_writepage;
+ }
+ 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);
+ attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
+ i_size = i_size_read(vi);
+ if (unlikely(attr_len > i_size)) {
+ /* Race with shrinking truncate or a failed truncate. */
+ attr_len = i_size;
+ /*
+ * If the truncate failed, fix it up now. If a concurrent
+ * truncate, we do its job, so it does not have to do anything.
+ */
+ err = ntfs_resident_attr_value_resize(ctx->mrec, ctx->attr,
+ attr_len);
+ /* Shrinking cannot fail. */
+ BUG_ON(err);
+ }
+ addr = kmap_atomic(page);
+ /* Copy the data from the page to the mft record. */
+ memcpy((u8*)ctx->attr +
+ le16_to_cpu(ctx->attr->data.resident.value_offset),
+ addr, attr_len);
+ /* Zero out of bounds area in the page cache page. */
+ memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
+ kunmap_atomic(addr);
+ flush_dcache_page(page);
+ flush_dcache_mft_record_page(ctx->ntfs_ino);
+ /* We are done with the page. */
+ end_page_writeback(page);
+ /* Finally, 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);
+ }
+ unlock_page(page);
+ if (ctx)
+ ntfs_attr_put_search_ctx(ctx);
+ if (m)
+ unmap_mft_record(base_ni);
+ return err;
+}
+
+#endif /* NTFS_RW */
+
+/**
+ * ntfs_bmap - map logical file block to physical device block
+ * @mapping: address space mapping to which the block to be mapped belongs
+ * @block: logical block to map to its physical device block
+ *
+ * For regular, non-resident files (i.e. not compressed and not encrypted), map
+ * the logical @block belonging to the file described by the address space
+ * mapping @mapping to its physical device block.
+ *
+ * The size of the block is equal to the @s_blocksize field of the super block
+ * of the mounted file system which is guaranteed to be smaller than or equal
+ * to the cluster size thus the block is guaranteed to fit entirely inside the
+ * cluster which means we do not need to care how many contiguous bytes are
+ * available after the beginning of the block.
+ *
+ * Return the physical device block if the mapping succeeded or 0 if the block
+ * is sparse or there was an error.
+ *
+ * Note: This is a problem if someone tries to run bmap() on $Boot system file
+ * as that really is in block zero but there is nothing we can do. bmap() is
+ * just broken in that respect (just like it cannot distinguish sparse from
+ * not available or error).
+ */
+static sector_t ntfs_bmap(struct address_space *mapping, sector_t block)
+{
+ s64 ofs, size;
+ loff_t i_size;
+ LCN lcn;
+ unsigned long blocksize, flags;
+ ntfs_inode *ni = NTFS_I(mapping->host);
+ ntfs_volume *vol = ni->vol;
+ unsigned delta;
+ unsigned char blocksize_bits, cluster_size_shift;
+
+ ntfs_debug("Entering for mft_no 0x%lx, logical block 0x%llx.",
+ ni->mft_no, (unsigned long long)block);
+ if (ni->type != AT_DATA || !NInoNonResident(ni) || NInoEncrypted(ni)) {
+ ntfs_error(vol->sb, "BMAP does not make sense for %s "
+ "attributes, returning 0.",
+ (ni->type != AT_DATA) ? "non-data" :
+ (!NInoNonResident(ni) ? "resident" :
+ "encrypted"));
+ return 0;
+ }
+ /* None of these can happen. */
+ BUG_ON(NInoCompressed(ni));
+ BUG_ON(NInoMstProtected(ni));
+ blocksize = vol->sb->s_blocksize;
+ blocksize_bits = vol->sb->s_blocksize_bits;
+ ofs = (s64)block << blocksize_bits;
+ read_lock_irqsave(&ni->size_lock, flags);
+ size = ni->initialized_size;
+ i_size = i_size_read(VFS_I(ni));
+ read_unlock_irqrestore(&ni->size_lock, flags);
+ /*
+ * If the offset is outside the initialized size or the block straddles
+ * the initialized size then pretend it is a hole unless the
+ * initialized size equals the file size.
+ */
+ if (unlikely(ofs >= size || (ofs + blocksize > size && size < i_size)))
+ goto hole;
+ cluster_size_shift = vol->cluster_size_bits;
+ down_read(&ni->runlist.lock);
+ lcn = ntfs_attr_vcn_to_lcn_nolock(ni, ofs >> cluster_size_shift, false);
+ up_read(&ni->runlist.lock);
+ if (unlikely(lcn < LCN_HOLE)) {
+ /*
+ * Step down to an integer to avoid gcc doing a long long
+ * comparision in the switch when we know @lcn is between
+ * LCN_HOLE and LCN_EIO (i.e. -1 to -5).
+ *
+ * Otherwise older gcc (at least on some architectures) will
+ * try to use __cmpdi2() which is of course not available in
+ * the kernel.
+ */
+ switch ((int)lcn) {
+ case LCN_ENOENT:
+ /*
+ * If the offset is out of bounds then pretend it is a
+ * hole.
+ */
+ goto hole;
+ case LCN_ENOMEM:
+ ntfs_error(vol->sb, "Not enough memory to complete "
+ "mapping for inode 0x%lx. "
+ "Returning 0.", ni->mft_no);
+ break;
+ default:
+ ntfs_error(vol->sb, "Failed to complete mapping for "
+ "inode 0x%lx. Run chkdsk. "
+ "Returning 0.", ni->mft_no);
+ break;
+ }
+ return 0;
+ }
+ if (lcn < 0) {
+ /* It is a hole. */
+hole:
+ ntfs_debug("Done (returning hole).");
+ return 0;
+ }
+ /*
+ * The block is really allocated and fullfils all our criteria.
+ * Convert the cluster to units of block size and return the result.
+ */
+ delta = ofs & vol->cluster_size_mask;
+ if (unlikely(sizeof(block) < sizeof(lcn))) {
+ block = lcn = ((lcn << cluster_size_shift) + delta) >>
+ blocksize_bits;
+ /* If the block number was truncated return 0. */
+ if (unlikely(block != lcn)) {
+ ntfs_error(vol->sb, "Physical block 0x%llx is too "
+ "large to be returned, returning 0.",
+ (long long)lcn);
+ return 0;
+ }
+ } else
+ block = ((lcn << cluster_size_shift) + delta) >>
+ blocksize_bits;
+ ntfs_debug("Done (returning block 0x%llx).", (unsigned long long)lcn);
+ return block;
+}
+
+/**
+ * ntfs_normal_aops - address space operations for normal inodes and attributes
+ *
+ * Note these are not used for compressed or mst protected inodes and
+ * attributes.
+ */
+const struct address_space_operations ntfs_normal_aops = {
+ .readpage = ntfs_readpage,
+#ifdef NTFS_RW
+ .writepage = ntfs_writepage,
+ .set_page_dirty = __set_page_dirty_buffers,
+#endif /* NTFS_RW */
+ .bmap = ntfs_bmap,
+ .migratepage = buffer_migrate_page,
+ .is_partially_uptodate = block_is_partially_uptodate,
+ .error_remove_page = generic_error_remove_page,
+};
+
+/**
+ * ntfs_compressed_aops - address space operations for compressed inodes
+ */
+const struct address_space_operations ntfs_compressed_aops = {
+ .readpage = ntfs_readpage,
+#ifdef NTFS_RW
+ .writepage = ntfs_writepage,
+ .set_page_dirty = __set_page_dirty_buffers,
+#endif /* NTFS_RW */
+ .migratepage = buffer_migrate_page,
+ .is_partially_uptodate = block_is_partially_uptodate,
+ .error_remove_page = generic_error_remove_page,
+};
+
+/**
+ * ntfs_mst_aops - general address space operations for mst protecteed inodes
+ * and attributes
+ */
+const struct address_space_operations ntfs_mst_aops = {
+ .readpage = ntfs_readpage, /* Fill page with data. */
+#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 */
+ .migratepage = buffer_migrate_page,
+ .is_partially_uptodate = block_is_partially_uptodate,
+ .error_remove_page = generic_error_remove_page,
+};
+
+#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 = VFS_I(ni)->i_sb->s_blocksize;
+ 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);
+ BUG_ON(!bh);
+ 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 */