NTFS: Remove address space operations ->prepare_write and ->commit_write in

      preparation for the big rewrite of write(2) support in ntfs.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/aops.c

@@ -1542,830 +1542,6 @@ err_out:
 	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;
-					if (!rl)
-						up_read(&ni->runlist.lock);
-					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;
-				} else if (!rl)
-					up_read(&ni->runlist.lock);
-				/*
-				 * 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);
-				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 */
 
 /**
@@ -2377,9 +1553,6 @@ struct address_space_operations ntfs_aops = {
 						   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 */
 };