1 files changed, 241 insertions, 153 deletions

diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 78adad7a988..5e80c07c6a4 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -27,6 +27,7 @@
 #include <linux/swap.h>
 #include <linux/buffer_head.h>
 #include <linux/writeback.h>
+#include <linux/bit_spinlock.h>
 
 #include "aops.h"
 #include "attrib.h"
@@ -55,45 +56,56 @@
  */
 static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 {
-	static DEFINE_SPINLOCK(page_uptodate_lock);
 	unsigned long flags;
-	struct buffer_head *tmp;
+	struct buffer_head *first, *tmp;
 	struct page *page;
+	struct inode *vi;
 	ntfs_inode *ni;
 	int page_uptodate = 1;
 
 	page = bh->b_page;
-	ni = NTFS_I(page->mapping->host);
+	vi = page->mapping->host;
+	ni = NTFS_I(vi);
 
 	if (likely(uptodate)) {
-		s64 file_ofs, initialized_size;
+		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);
-		initialized_size = ni->initialized_size;
+		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 (file_ofs + bh->b_size > initialized_size) {
-			char *addr;
-			int ofs = 0;
-
-			if (file_ofs < initialized_size)
-				ofs = initialized_size - file_ofs;
-			addr = kmap_atomic(page, KM_BIO_SRC_IRQ);
-			memset(addr + bh_offset(bh) + ofs, 0, bh->b_size - ofs);
+		if (unlikely(file_ofs + bh->b_size > init_size)) {
+			u8 *kaddr;
+			int ofs;
+
+			ofs = 0;
+			if (file_ofs < init_size)
+				ofs = init_size - file_ofs;
+			kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ);
+			memset(kaddr + bh_offset(bh) + ofs, 0,
+					bh->b_size - ofs);
+			kunmap_atomic(kaddr, KM_BIO_SRC_IRQ);
 			flush_dcache_page(page);
-			kunmap_atomic(addr, KM_BIO_SRC_IRQ);
 		}
 	} else {
 		clear_buffer_uptodate(bh);
-		ntfs_error(ni->vol->sb, "Buffer I/O error, logical block %llu.",
-				(unsigned long long)bh->b_blocknr);
 		SetPageError(page);
+		ntfs_error(ni->vol->sb, "Buffer I/O error, logical block "
+				"0x%llx.", (unsigned long long)bh->b_blocknr);
 	}
-	spin_lock_irqsave(&page_uptodate_lock, flags);
+	first = page_buffers(page);
+	local_irq_save(flags);
+	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
 	clear_buffer_async_read(bh);
 	unlock_buffer(bh);
 	tmp = bh;
@@ -108,7 +120,8 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 		}
 		tmp = tmp->b_this_page;
 	} while (tmp != bh);
-	spin_unlock_irqrestore(&page_uptodate_lock, flags);
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(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
@@ -121,7 +134,7 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 		if (likely(page_uptodate && !PageError(page)))
 			SetPageUptodate(page);
 	} else {
-		char *addr;
+		u8 *kaddr;
 		unsigned int i, recs;
 		u32 rec_size;
 
@@ -129,19 +142,20 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 		recs = PAGE_CACHE_SIZE / rec_size;
 		/* Should have been verified before we got here... */
 		BUG_ON(!recs);
-		addr = kmap_atomic(page, KM_BIO_SRC_IRQ);
+		kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ);
 		for (i = 0; i < recs; i++)
-			post_read_mst_fixup((NTFS_RECORD*)(addr +
+			post_read_mst_fixup((NTFS_RECORD*)(kaddr +
 					i * rec_size), rec_size);
+		kunmap_atomic(kaddr, KM_BIO_SRC_IRQ);
 		flush_dcache_page(page);
-		kunmap_atomic(addr, KM_BIO_SRC_IRQ);
 		if (likely(page_uptodate && !PageError(page)))
 			SetPageUptodate(page);
 	}
 	unlock_page(page);
 	return;
 still_busy:
-	spin_unlock_irqrestore(&page_uptodate_lock, flags);
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
 	return;
 }
 
@@ -164,8 +178,11 @@ still_busy:
  */
 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;
@@ -176,7 +193,8 @@ static int ntfs_read_block(struct page *page)
 	int i, nr;
 	unsigned char blocksize_bits;
 
-	ni = NTFS_I(page->mapping->host);
+	vi = page->mapping->host;
+	ni = NTFS_I(vi);
 	vol = ni->vol;
 
 	/* $MFT/$DATA must have its complete runlist in memory at all times. */
@@ -185,25 +203,45 @@ static int ntfs_read_block(struct page *page)
 	blocksize_bits = VFS_I(ni)->i_blkbits;
 	blocksize = 1 << blocksize_bits;
 
-	if (!page_has_buffers(page))
+	if (!page_has_buffers(page)) {
 		create_empty_buffers(page, blocksize, 0);
-	bh = head = page_buffers(page);
-	if (unlikely(!bh)) {
-		unlock_page(page);
-		return -ENOMEM;
+		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;
-	zblock = (ni->initialized_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 {
 		u8 *kaddr;
+		int err;
 
 		if (unlikely(buffer_uptodate(bh)))
 			continue;
@@ -211,6 +249,7 @@ static int ntfs_read_block(struct page *page)
 			arr[nr++] = bh;
 			continue;
 		}
+		err = 0;
 		bh->b_bdev = vol->sb->s_bdev;
 		/* Is the block within the allowed limits? */
 		if (iblock < lblock) {
@@ -252,7 +291,6 @@ lock_retry_remap:
 				goto handle_hole;
 			/* If first try and runlist unmapped, map and retry. */
 			if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
-				int err;
 				is_retry = TRUE;
 				/*
 				 * Attempt to map runlist, dropping lock for
@@ -263,20 +301,30 @@ lock_retry_remap:
 				if (likely(!err))
 					goto lock_retry_remap;
 				rl = NULL;
-				lcn = err;
 			} 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 %lli).", ni->mft_no,
+					"(error code %i).", ni->mft_no,
 					ni->type, (unsigned long long)vcn,
 					vcn_ofs, is_retry ? " even after "
-					"retrying" : "", (long long)lcn);
+					"retrying" : "", err);
 		}
 		/*
 		 * Either iblock was outside lblock limits or
@@ -289,9 +337,10 @@ handle_hole:
 handle_zblock:
 		kaddr = kmap_atomic(page, KM_USER0);
 		memset(kaddr + i * blocksize, 0, blocksize);
-		flush_dcache_page(page);
 		kunmap_atomic(kaddr, KM_USER0);
-		set_buffer_uptodate(bh);
+		flush_dcache_page(page);
+		if (likely(!err))
+			set_buffer_uptodate(bh);
 	} while (i++, iblock++, (bh = bh->b_this_page) != head);
 
 	/* Release the lock if we took it. */
@@ -348,6 +397,8 @@ handle_zblock:
  */
 static int ntfs_readpage(struct file *file, struct page *page)
 {
+	loff_t i_size;
+	struct inode *vi;
 	ntfs_inode *ni, *base_ni;
 	u8 *kaddr;
 	ntfs_attr_search_ctx *ctx;
@@ -366,32 +417,42 @@ retry_readpage:
 		unlock_page(page);
 		return 0;
 	}
-	ni = NTFS_I(page->mapping->host);
-
+	vi = page->mapping->host;
+	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)) {
-		/*
-		 * Only unnamed $DATA attributes can be compressed or
-		 * encrypted.
-		 */
-		if (ni->type == AT_DATA && !ni->name_len) {
-			/* If file is encrypted, deny access, just like NT4. */
-			if (NInoEncrypted(ni)) {
-				err = -EACCES;
-				goto err_out;
-			}
-			/* Compressed data streams are handled in compress.c. */
-			if (NInoCompressed(ni))
-				return ntfs_read_compressed_block(page);
-		}
-		/* Normal data stream. */
+		/* 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.
+	 * 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)) {
 		kaddr = kmap_atomic(page, KM_USER0);
@@ -431,7 +492,12 @@ retry_readpage:
 	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;
+	}
 	kaddr = kmap_atomic(page, KM_USER0);
 	/* Copy the data to the page. */
 	memcpy(kaddr, (u8*)ctx->attr +
@@ -511,19 +577,21 @@ static int ntfs_write_block(struct page *page, struct writeback_control *wbc)
 		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);
-	if (unlikely(!bh)) {
-		ntfs_warning(vol->sb, "Error allocating page buffers. "
-				"Redirtying page so we try again later.");
-		/*
-		 * Put the page back on mapping->dirty_pages, but leave its
-		 * buffer's dirty state as-is.
-		 */
-		redirty_page_for_writepage(wbc, page);
-		unlock_page(page);
-		return 0;
-	}
+	BUG_ON(!bh);
 
 	/* NOTE: Different naming scheme to ntfs_read_block()! */
 
@@ -670,6 +738,27 @@ lock_retry_remap:
 		}
 		/* 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, KM_USER0);
+			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, KM_USER0);
+			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);
@@ -690,20 +779,37 @@ lock_retry_remap:
 			if (likely(!err))
 				goto lock_retry_remap;
 			rl = NULL;
-			lcn = err;
 		} 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) {
+			u8 *kaddr;
+
+			bh->b_blocknr = -1;
+			clear_buffer_dirty(bh);
+			kaddr = kmap_atomic(page, KM_USER0);
+			memset(kaddr + bh_offset(bh), 0, blocksize);
+			kunmap_atomic(kaddr, KM_USER0);
+			flush_dcache_page(page);
+			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 %lli).", ni->mft_no,
+				"determined%s (error code %i).", ni->mft_no,
 				ni->type, (unsigned long long)vcn,
 				vcn_ofs, is_retry ? " even after "
-				"retrying" : "", (long long)lcn);
-		if (!err)
-			err = -EIO;
+				"retrying" : "", err);
 		break;
 	} while (block++, (bh = bh->b_this_page) != head);
 
@@ -714,7 +820,7 @@ lock_retry_remap:
 	/* For the error case, need to reset bh to the beginning. */
 	bh = head;
 
-	/* Just an optimization, so ->readpage() isn't called later. */
+	/* Just an optimization, so ->readpage() is not called later. */
 	if (unlikely(!PageUptodate(page))) {
 		int uptodate = 1;
 		do {
@@ -730,7 +836,6 @@ lock_retry_remap:
 
 	/* Setup all mapped, dirty buffers for async write i/o. */
 	do {
-		get_bh(bh);
 		if (buffer_mapped(bh) && buffer_dirty(bh)) {
 			lock_buffer(bh);
 			if (test_clear_buffer_dirty(bh)) {
@@ -768,14 +873,8 @@ lock_retry_remap:
 
 	BUG_ON(PageWriteback(page));
 	set_page_writeback(page);	/* Keeps try_to_free_buffers() away. */
-	unlock_page(page);
 
-	/*
-	 * Submit the prepared buffers for i/o. Note the page is unlocked,
-	 * and the async write i/o completion handler can end_page_writeback()
-	 * at any time after the *first* submit_bh(). So the buffers can then
-	 * disappear...
-	 */
+	/* Submit the prepared buffers for i/o. */
 	need_end_writeback = TRUE;
 	do {
 		struct buffer_head *next = bh->b_this_page;
@@ -783,9 +882,9 @@ lock_retry_remap:
 			submit_bh(WRITE, bh);
 			need_end_writeback = FALSE;
 		}
-		put_bh(bh);
 		bh = next;
 	} while (bh != head);
+	unlock_page(page);
 
 	/* If no i/o was started, need to end_page_writeback(). */
 	if (unlikely(need_end_writeback))
@@ -860,7 +959,6 @@ static int ntfs_write_mst_block(struct page *page,
 	sync = (wbc->sync_mode == WB_SYNC_ALL);
 
 	/* Make sure we have mapped buffers. */
-	BUG_ON(!page_has_buffers(page));
 	bh = head = page_buffers(page);
 	BUG_ON(!bh);
 
@@ -1280,58 +1378,66 @@ retry_writepage:
 		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)) {
-		/*
-		 * Only unnamed $DATA attributes can be compressed, encrypted,
-		 * and/or sparse.
-		 */
-		if (ni->type == AT_DATA && !ni->name_len) {
-			/* If file is encrypted, deny access, just like NT4. */
-			if (NInoEncrypted(ni)) {
-				unlock_page(page);
-				ntfs_debug("Denying write access to encrypted "
-						"file.");
-				return -EACCES;
-			}
-			/* Compressed data streams are handled in compress.c. */
-			if (NInoCompressed(ni)) {
-				// TODO: Implement and replace this check with
-				// return ntfs_write_compressed_block(page);
-				unlock_page(page);
-				ntfs_error(vi->i_sb, "Writing to compressed "
-						"files is not supported yet. "
-						"Sorry.");
-				return -EOPNOTSUPP;
-			}
-			// TODO: Implement and remove this check.
-			if (NInoSparse(ni)) {
-				unlock_page(page);
-				ntfs_error(vi->i_sb, "Writing to sparse files "
-						"is not supported yet. Sorry.");
-				return -EOPNOTSUPP;
-			}
-		}
 		/* We have to zero every time due to mmap-at-end-of-file. */
 		if (page->index >= (i_size >> PAGE_CACHE_SHIFT)) {
 			/* The page straddles i_size. */
 			unsigned int ofs = i_size & ~PAGE_CACHE_MASK;
 			kaddr = kmap_atomic(page, KM_USER0);
 			memset(kaddr + ofs, 0, PAGE_CACHE_SIZE - ofs);
-			flush_dcache_page(page);
 			kunmap_atomic(kaddr, KM_USER0);
+			flush_dcache_page(page);
 		}
 		/* Handle mst protected attributes. */
 		if (NInoMstProtected(ni))
 			return ntfs_write_mst_block(page, wbc);
-		/* Normal data stream. */
+		/* Normal, non-resident data stream. */
 		return ntfs_write_block(page, wbc);
 	}
 	/*
-	 * Attribute is resident, implying it is not compressed, encrypted,
-	 * sparse, or mst protected.  This also means the attribute is smaller
-	 * than an mft record and hence smaller than a page, so can simply
-	 * return error on any pages with index above 0.
+	 * 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));
@@ -1380,50 +1486,33 @@ retry_writepage:
 	BUG_ON(PageWriteback(page));
 	set_page_writeback(page);
 	unlock_page(page);
-
-	/*
-	 * Here, we don't need to zero the out of bounds area everytime because
-	 * the below memcpy() already takes care of the mmap-at-end-of-file
-	 * requirements. If the file is converted to a non-resident one, then
-	 * the code path use is switched to the non-resident one where the
-	 * zeroing happens on each ntfs_writepage() invocation.
-	 *
-	 * The above also applies nicely when i_size is decreased.
-	 *
-	 * When i_size is increased, the memory between the old and new i_size
-	 * _must_ be zeroed (or overwritten with new data). Otherwise we will
-	 * expose data to userspace/disk which should never have been exposed.
-	 *
-	 * FIXME: Ensure that i_size increases do the zeroing/overwriting and
-	 * if we cannot guarantee that, then enable the zeroing below.  If the
-	 * zeroing below is enabled, we MUST move the unlock_page() from above
-	 * to after the kunmap_atomic(), i.e. just before the
-	 * end_page_writeback().
-	 * UPDATE: ntfs_prepare/commit_write() do the zeroing on i_size
-	 * increases for resident attributes so those are ok.
-	 * TODO: ntfs_truncate(), others?
-	 */
-
 	attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
 	i_size = i_size_read(vi);
 	if (unlikely(attr_len > i_size)) {
+		/* Race with shrinking truncate or a failed truncate. */
 		attr_len = i_size;
-		ctx->attr->data.resident.value_length = cpu_to_le32(attr_len);
+		/*
+		 * 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);
 	}
 	kaddr = kmap_atomic(page, KM_USER0);
 	/* Copy the data from the page to the mft record. */
 	memcpy((u8*)ctx->attr +
 			le16_to_cpu(ctx->attr->data.resident.value_offset),
 			kaddr, attr_len);
-	flush_dcache_mft_record_page(ctx->ntfs_ino);
 	/* Zero out of bounds area in the page cache page. */
 	memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
-	flush_dcache_page(page);
 	kunmap_atomic(kaddr, KM_USER0);
-
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	flush_dcache_page(page);
+	/* We are done with the page. */
 	end_page_writeback(page);
-
-	/* Mark the mft record dirty, so it gets written back. */
+	/* 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);
@@ -1681,27 +1770,25 @@ lock_retry_remap:
 					if (likely(!err))
 						goto lock_retry_remap;
 					rl = NULL;
-					lcn = err;
 				} 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 %lli).",
+						"(error code %i).",
 						ni->mft_no, ni->type,
 						(unsigned long long)vcn,
 						vcn_ofs, is_retry ? " even "
-						"after retrying" : "",
-						(long long)lcn);
-				if (!err)
-					err = -EIO;
+						"after retrying" : "", err);
 				goto err_out;
 			}
 			/* We now have a successful remap, i.e. lcn >= 0. */
@@ -2357,6 +2444,7 @@ void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs) {
 			buffers_to_free = bh;
 	}
 	bh = head = page_buffers(page);
+	BUG_ON(!bh);
 	do {
 		bh_ofs = bh_offset(bh);
 		if (bh_ofs + bh_size <= ofs)