NTFS: Version 2.1.32 - Update file write from aio_write to write_iter.

Signed-off-by: Anton Altaparmakov <anton@tuxera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 308 insertions, 477 deletions

diff --git a/fs/ntfs/Makefile b/fs/ntfs/Makefile
index 36ae529511c4..2ff263e6d363 100644
--- a/fs/ntfs/Makefile
+++ b/fs/ntfs/Makefile
@@ -8,7 +8,7 @@ ntfs-y := aops.o attrib.o collate.o compress.o debug.o dir.o file.o \
 
 ntfs-$(CONFIG_NTFS_RW) += bitmap.o lcnalloc.o logfile.o quota.o usnjrnl.o
 
-ccflags-y := -DNTFS_VERSION=\"2.1.31\"
+ccflags-y := -DNTFS_VERSION=\"2.1.32\"
 ccflags-$(CONFIG_NTFS_DEBUG)	+= -DDEBUG
 ccflags-$(CONFIG_NTFS_RW)	+= -DNTFS_RW
 
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 1da9b2d184dc..29139ffb4328 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -1,7 +1,7 @@
 /*
  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2014 Anton Altaparmakov and Tuxera Inc.
+ * Copyright (c) 2001-2015 Anton Altaparmakov and Tuxera Inc.
  *
  * 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
@@ -329,62 +329,168 @@ err_out:
 	return err;
 }
 
-/**
- * ntfs_fault_in_pages_readable -
- *
- * Fault a number of userspace pages into pagetables.
- *
- * Unlike include/linux/pagemap.h::fault_in_pages_readable(), this one copes
- * with more than two userspace pages as well as handling the single page case
- * elegantly.
- *
- * If you find this difficult to understand, then think of the while loop being
- * the following code, except that we do without the integer variable ret:
- *
- *	do {
- *		ret = __get_user(c, uaddr);
- *		uaddr += PAGE_SIZE;
- *	} while (!ret && uaddr < end);
- *
- * Note, the final __get_user() may well run out-of-bounds of the user buffer,
- * but _not_ out-of-bounds of the page the user buffer belongs to, and since
- * this is only a read and not a write, and since it is still in the same page,
- * it should not matter and this makes the code much simpler.
- */
-static inline void ntfs_fault_in_pages_readable(const char __user *uaddr,
-		int bytes)
+static ssize_t ntfs_prepare_file_for_write(struct file *file, loff_t *ppos,
+		size_t *count)
 {
-	const char __user *end;
-	volatile char c;
-
-	/* Set @end to the first byte outside the last page we care about. */
-	end = (const char __user*)PAGE_ALIGN((unsigned long)uaddr + bytes);
-
-	while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
-		;
-}
-
-/**
- * ntfs_fault_in_pages_readable_iovec -
- *
- * Same as ntfs_fault_in_pages_readable() but operates on an array of iovecs.
- */
-static inline void ntfs_fault_in_pages_readable_iovec(const struct iovec *iov,
-		size_t iov_ofs, int bytes)
-{
-	do {
-		const char __user *buf;
-		unsigned len;
+	loff_t pos;
+	s64 end, ll;
+	ssize_t err;
+	unsigned long flags;
+	struct inode *vi = file_inode(file);
+	ntfs_inode *base_ni, *ni = NTFS_I(vi);
+	ntfs_volume *vol = ni->vol;
 
-		buf = iov->iov_base + iov_ofs;
-		len = iov->iov_len - iov_ofs;
-		if (len > bytes)
-			len = bytes;
-		ntfs_fault_in_pages_readable(buf, len);
-		bytes -= len;
-		iov++;
-		iov_ofs = 0;
-	} while (bytes);
+	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
+			"0x%llx, count 0x%lx.", vi->i_ino,
+			(unsigned)le32_to_cpu(ni->type),
+			(unsigned long long)*ppos, (unsigned long)*count);
+	/* We can write back this queue in page reclaim. */
+	current->backing_dev_info = inode_to_bdi(vi);
+	err = generic_write_checks(file, ppos, count, S_ISBLK(vi->i_mode));
+	if (unlikely(err))
+		goto out;
+	/*
+	 * All checks have passed.  Before we start doing any writing we want
+	 * to abort any totally illegal writes.
+	 */
+	BUG_ON(NInoMstProtected(ni));
+	BUG_ON(ni->type != AT_DATA);
+	/* If file is encrypted, deny access, just like NT4. */
+	if (NInoEncrypted(ni)) {
+		/* Only $DATA attributes can be encrypted. */
+		/*
+		 * Reminder for later: Encrypted files are _always_
+		 * non-resident so that the content can always be encrypted.
+		 */
+		ntfs_debug("Denying write access to encrypted file.");
+		err = -EACCES;
+		goto out;
+	}
+	if (NInoCompressed(ni)) {
+		/* Only unnamed $DATA attribute can be compressed. */
+		BUG_ON(ni->name_len);
+		/*
+		 * Reminder for later: If resident, the data is not actually
+		 * compressed.  Only on the switch to non-resident does
+		 * compression kick in.  This is in contrast to encrypted files
+		 * (see above).
+		 */
+		ntfs_error(vi->i_sb, "Writing to compressed files is not "
+				"implemented yet.  Sorry.");
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+	if (*count == 0)
+		goto out;
+	base_ni = ni;
+	if (NInoAttr(ni))
+		base_ni = ni->ext.base_ntfs_ino;
+	err = file_remove_suid(file);
+	if (unlikely(err))
+		goto out;
+	/*
+	 * Our ->update_time method always succeeds thus file_update_time()
+	 * cannot fail either so there is no need to check the return code.
+	 */
+	file_update_time(file);
+	pos = *ppos;
+	/* The first byte after the last cluster being written to. */
+	end = (pos + *count + vol->cluster_size_mask) &
+			~(u64)vol->cluster_size_mask;
+	/*
+	 * If the write goes beyond the allocated size, extend the allocation
+	 * to cover the whole of the write, rounded up to the nearest cluster.
+	 */
+	read_lock_irqsave(&ni->size_lock, flags);
+	ll = ni->allocated_size;
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	if (end > ll) {
+		/*
+		 * Extend the allocation without changing the data size.
+		 *
+		 * Note we ensure the allocation is big enough to at least
+		 * write some data but we do not require the allocation to be
+		 * complete, i.e. it may be partial.
+		 */
+		ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
+		if (likely(ll >= 0)) {
+			BUG_ON(pos >= ll);
+			/* If the extension was partial truncate the write. */
+			if (end > ll) {
+				ntfs_debug("Truncating write to inode 0x%lx, "
+						"attribute type 0x%x, because "
+						"the allocation was only "
+						"partially extended.",
+						vi->i_ino, (unsigned)
+						le32_to_cpu(ni->type));
+				*count = ll - pos;
+			}
+		} else {
+			err = ll;
+			read_lock_irqsave(&ni->size_lock, flags);
+			ll = ni->allocated_size;
+			read_unlock_irqrestore(&ni->size_lock, flags);
+			/* Perform a partial write if possible or fail. */
+			if (pos < ll) {
+				ntfs_debug("Truncating write to inode 0x%lx "
+						"attribute type 0x%x, because "
+						"extending the allocation "
+						"failed (error %d).",
+						vi->i_ino, (unsigned)
+						le32_to_cpu(ni->type),
+						(int)-err);
+				*count = ll - pos;
+			} else {
+				if (err != -ENOSPC)
+					ntfs_error(vi->i_sb, "Cannot perform "
+							"write to inode "
+							"0x%lx, attribute "
+							"type 0x%x, because "
+							"extending the "
+							"allocation failed "
+							"(error %ld).",
+							vi->i_ino, (unsigned)
+							le32_to_cpu(ni->type),
+							(long)-err);
+				else
+					ntfs_debug("Cannot perform write to "
+							"inode 0x%lx, "
+							"attribute type 0x%x, "
+							"because there is not "
+							"space left.",
+							vi->i_ino, (unsigned)
+							le32_to_cpu(ni->type));
+				goto out;
+			}
+		}
+	}
+	/*
+	 * If the write starts beyond the initialized size, extend it up to the
+	 * beginning of the write and initialize all non-sparse space between
+	 * the old initialized size and the new one.  This automatically also
+	 * increments the vfs inode->i_size to keep it above or equal to the
+	 * initialized_size.
+	 */
+	read_lock_irqsave(&ni->size_lock, flags);
+	ll = ni->initialized_size;
+	read_unlock_irqrestore(&ni->size_lock, flags);
+	if (pos > ll) {
+		/*
+		 * Wait for ongoing direct i/o to complete before proceeding.
+		 * New direct i/o cannot start as we hold i_mutex.
+		 */
+		inode_dio_wait(vi);
+		err = ntfs_attr_extend_initialized(ni, pos);
+		if (unlikely(err < 0))
+			ntfs_error(vi->i_sb, "Cannot perform write to inode "
+					"0x%lx, attribute type 0x%x, because "
+					"extending the initialized size "
+					"failed (error %d).", vi->i_ino,
+					(unsigned)le32_to_cpu(ni->type),
+					(int)-err);
+	}
+out:
+	return err;
 }
 
 /**
@@ -421,8 +527,8 @@ static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
 					goto err_out;
 				}
 			}
-			err = add_to_page_cache_lru(*cached_page, mapping, index,
-					GFP_KERNEL);
+			err = add_to_page_cache_lru(*cached_page, mapping,
+					index, GFP_KERNEL);
 			if (unlikely(err)) {
 				if (err == -EEXIST)
 					continue;
@@ -1268,180 +1374,6 @@ rl_not_mapped_enoent:
 	return err;
 }
 
-/*
- * Copy as much as we can into the pages and return the number of bytes which
- * were successfully copied.  If a fault is encountered then clear the pages
- * out to (ofs + bytes) and return the number of bytes which were copied.
- */
-static inline size_t ntfs_copy_from_user(struct page **pages,
-		unsigned nr_pages, unsigned ofs, const char __user *buf,
-		size_t bytes)
-{
-	struct page **last_page = pages + nr_pages;
-	char *addr;
-	size_t total = 0;
-	unsigned len;
-	int left;
-
-	do {
-		len = PAGE_CACHE_SIZE - ofs;
-		if (len > bytes)
-			len = bytes;
-		addr = kmap_atomic(*pages);
-		left = __copy_from_user_inatomic(addr + ofs, buf, len);
-		kunmap_atomic(addr);
-		if (unlikely(left)) {
-			/* Do it the slow way. */
-			addr = kmap(*pages);
-			left = __copy_from_user(addr + ofs, buf, len);
-			kunmap(*pages);
-			if (unlikely(left))
-				goto err_out;
-		}
-		total += len;
-		bytes -= len;
-		if (!bytes)
-			break;
-		buf += len;
-		ofs = 0;
-	} while (++pages < last_page);
-out:
-	return total;
-err_out:
-	total += len - left;
-	/* Zero the rest of the target like __copy_from_user(). */
-	while (++pages < last_page) {
-		bytes -= len;
-		if (!bytes)
-			break;
-		len = PAGE_CACHE_SIZE;
-		if (len > bytes)
-			len = bytes;
-		zero_user(*pages, 0, len);
-	}
-	goto out;
-}
-
-static size_t __ntfs_copy_from_user_iovec_inatomic(char *vaddr,
-		const struct iovec *iov, size_t iov_ofs, size_t bytes)
-{
-	size_t total = 0;
-
-	while (1) {
-		const char __user *buf = iov->iov_base + iov_ofs;
-		unsigned len;
-		size_t left;
-
-		len = iov->iov_len - iov_ofs;
-		if (len > bytes)
-			len = bytes;
-		left = __copy_from_user_inatomic(vaddr, buf, len);
-		total += len;
-		bytes -= len;
-		vaddr += len;
-		if (unlikely(left)) {
-			total -= left;
-			break;
-		}
-		if (!bytes)
-			break;
-		iov++;
-		iov_ofs = 0;
-	}
-	return total;
-}
-
-static inline void ntfs_set_next_iovec(const struct iovec **iovp,
-		size_t *iov_ofsp, size_t bytes)
-{
-	const struct iovec *iov = *iovp;
-	size_t iov_ofs = *iov_ofsp;
-
-	while (bytes) {
-		unsigned len;
-
-		len = iov->iov_len - iov_ofs;
-		if (len > bytes)
-			len = bytes;
-		bytes -= len;
-		iov_ofs += len;
-		if (iov->iov_len == iov_ofs) {
-			iov++;
-			iov_ofs = 0;
-		}
-	}
-	*iovp = iov;
-	*iov_ofsp = iov_ofs;
-}
-
-/*
- * This has the same side-effects and return value as ntfs_copy_from_user().
- * The difference is that on a fault we need to memset the remainder of the
- * pages (out to offset + bytes), to emulate ntfs_copy_from_user()'s
- * single-segment behaviour.
- *
- * We call the same helper (__ntfs_copy_from_user_iovec_inatomic()) both when
- * atomic and when not atomic.  This is ok because it calls
- * __copy_from_user_inatomic() and it is ok to call this when non-atomic.  In
- * fact, the only difference between __copy_from_user_inatomic() and
- * __copy_from_user() is that the latter calls might_sleep() and the former
- * should not zero the tail of the buffer on error.  And on many architectures
- * __copy_from_user_inatomic() is just defined to __copy_from_user() so it
- * makes no difference at all on those architectures.
- */
-static inline size_t ntfs_copy_from_user_iovec(struct page **pages,
-		unsigned nr_pages, unsigned ofs, const struct iovec **iov,
-		size_t *iov_ofs, size_t bytes)
-{
-	struct page **last_page = pages + nr_pages;
-	char *addr;
-	size_t copied, len, total = 0;
-
-	do {
-		len = PAGE_CACHE_SIZE - ofs;
-		if (len > bytes)
-			len = bytes;
-		addr = kmap_atomic(*pages);
-		copied = __ntfs_copy_from_user_iovec_inatomic(addr + ofs,
-				*iov, *iov_ofs, len);
-		kunmap_atomic(addr);
-		if (unlikely(copied != len)) {
-			/* Do it the slow way. */
-			addr = kmap(*pages);
-			copied = __ntfs_copy_from_user_iovec_inatomic(addr +
-					ofs, *iov, *iov_ofs, len);
-			if (unlikely(copied != len))
-				goto err_out;
-			kunmap(*pages);
-		}
-		total += len;
-		ntfs_set_next_iovec(iov, iov_ofs, len);
-		bytes -= len;
-		if (!bytes)
-			break;
-		ofs = 0;
-	} while (++pages < last_page);
-out:
-	return total;
-err_out:
-	BUG_ON(copied > len);
-	/* Zero the rest of the target like __copy_from_user(). */
-	memset(addr + ofs + copied, 0, len - copied);
-	kunmap(*pages);
-	total += copied;
-	ntfs_set_next_iovec(iov, iov_ofs, copied);
-	while (++pages < last_page) {
-		bytes -= len;
-		if (!bytes)
-			break;
-		len = PAGE_CACHE_SIZE;
-		if (len > bytes)
-			len = bytes;
-		zero_user(*pages, 0, len);
-	}
-	goto out;
-}
-
 static inline void ntfs_flush_dcache_pages(struct page **pages,
 		unsigned nr_pages)
 {
@@ -1762,86 +1694,83 @@ err_out:
 	return err;
 }
 
-static void ntfs_write_failed(struct address_space *mapping, loff_t to)
+/*
+ * Copy as much as we can into the pages and return the number of bytes which
+ * were successfully copied.  If a fault is encountered then clear the pages
+ * out to (ofs + bytes) and return the number of bytes which were copied.
+ */
+static size_t ntfs_copy_from_user_iter(struct page **pages, unsigned nr_pages,
+		unsigned ofs, struct iov_iter *i, size_t bytes)
 {
-	struct inode *inode = mapping->host;
+	struct page **last_page = pages + nr_pages;
+	size_t total = 0;
+	struct iov_iter data = *i;
+	unsigned len, copied;
 
-	if (to > inode->i_size) {
-		truncate_pagecache(inode, inode->i_size);
-		ntfs_truncate_vfs(inode);
-	}
+	do {
+		len = PAGE_CACHE_SIZE - ofs;
+		if (len > bytes)
+			len = bytes;
+		copied = iov_iter_copy_from_user_atomic(*pages, &data, ofs,
+				len);
+		total += copied;
+		bytes -= copied;
+		if (!bytes)
+			break;
+		iov_iter_advance(&data, copied);
+		if (copied < len)
+			goto err;
+		ofs = 0;
+	} while (++pages < last_page);
+out:
+	return total;
+err:
+	/* Zero the rest of the target like __copy_from_user(). */
+	len = PAGE_CACHE_SIZE - copied;
+	do {
+		if (len > bytes)
+			len = bytes;
+		zero_user(*pages, copied, len);
+		bytes -= len;
+		copied = 0;
+		len = PAGE_CACHE_SIZE;
+	} while (++pages < last_page);
+	goto out;
 }
 
 /**
- * ntfs_file_buffered_write -
- *
- * Locking: The vfs is holding ->i_mutex on the inode.
+ * ntfs_perform_write - perform buffered write to a file
+ * @file:	file to write to
+ * @i:		iov_iter with data to write
+ * @pos:	byte offset in file at which to begin writing to
  */
-static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
-		const struct iovec *iov, unsigned long nr_segs,
-		loff_t pos, loff_t *ppos, size_t count)
+static ssize_t ntfs_perform_write(struct file *file, struct iov_iter *i,
+		loff_t pos)
 {
-	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 	struct inode *vi = mapping->host;
 	ntfs_inode *ni = NTFS_I(vi);
 	ntfs_volume *vol = ni->vol;
 	struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
 	struct page *cached_page = NULL;
-	char __user *buf = NULL;
-	s64 end, ll;
 	VCN last_vcn;
 	LCN lcn;
-	unsigned long flags;
-	size_t bytes, iov_ofs = 0;	/* Offset in the current iovec. */
-	ssize_t status, written;
+	size_t bytes;
+	ssize_t status, written = 0;
 	unsigned nr_pages;
-	int err;
 
-	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
-			"pos 0x%llx, count 0x%lx.",
-			vi->i_ino, (unsigned)le32_to_cpu(ni->type),
-			(unsigned long long)pos, (unsigned long)count);
-	if (unlikely(!count))
-		return 0;
-	BUG_ON(NInoMstProtected(ni));
-	/*
-	 * If the attribute is not an index root and it is encrypted or
-	 * compressed, we cannot write to it yet.  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)) {
-			/*
-			 * Reminder for later: Encrypted files are _always_
-			 * non-resident so that the content can always be
-			 * encrypted.
-			 */
-			ntfs_debug("Denying write access to encrypted file.");
-			return -EACCES;
-		}
-		if (NInoCompressed(ni)) {
-			/* Only unnamed $DATA attribute can be compressed. */
-			BUG_ON(ni->type != AT_DATA);
-			BUG_ON(ni->name_len);
-			/*
-			 * Reminder for later: If resident, the data is not
-			 * actually compressed.  Only on the switch to non-
-			 * resident does compression kick in.  This is in
-			 * contrast to encrypted files (see above).
-			 */
-			ntfs_error(vi->i_sb, "Writing to compressed files is "
-					"not implemented yet.  Sorry.");
-			return -EOPNOTSUPP;
-		}
-	}
+	ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
+			"0x%llx, count 0x%lx.", vi->i_ino,
+			(unsigned)le32_to_cpu(ni->type),
+			(unsigned long long)pos,
+			(unsigned long)iov_iter_count(i));
 	/*
 	 * If a previous ntfs_truncate() failed, repeat it and abort if it
 	 * fails again.
 	 */
 	if (unlikely(NInoTruncateFailed(ni))) {
+		int err;
+
 		inode_dio_wait(vi);
 		err = ntfs_truncate(vi);
 		if (err || NInoTruncateFailed(ni)) {
@@ -1855,81 +1784,6 @@ static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
 			return err;
 		}
 	}
-	/* The first byte after the write. */
-	end = pos + count;
-	/*
-	 * If the write goes beyond the allocated size, extend the allocation
-	 * to cover the whole of the write, rounded up to the nearest cluster.
-	 */
-	read_lock_irqsave(&ni->size_lock, flags);
-	ll = ni->allocated_size;
-	read_unlock_irqrestore(&ni->size_lock, flags);
-	if (end > ll) {
-		/* Extend the allocation without changing the data size. */
-		ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
-		if (likely(ll >= 0)) {
-			BUG_ON(pos >= ll);
-			/* If the extension was partial truncate the write. */
-			if (end > ll) {
-				ntfs_debug("Truncating write to inode 0x%lx, "
-						"attribute type 0x%x, because "
-						"the allocation was only "
-						"partially extended.",
-						vi->i_ino, (unsigned)
-						le32_to_cpu(ni->type));
-				end = ll;
-				count = ll - pos;
-			}
-		} else {
-			err = ll;
-			read_lock_irqsave(&ni->size_lock, flags);
-			ll = ni->allocated_size;
-			read_unlock_irqrestore(&ni->size_lock, flags);
-			/* Perform a partial write if possible or fail. */
-			if (pos < ll) {
-				ntfs_debug("Truncating write to inode 0x%lx, "
-						"attribute type 0x%x, because "
-						"extending the allocation "
-						"failed (error code %i).",
-						vi->i_ino, (unsigned)
-						le32_to_cpu(ni->type), err);
-				end = ll;
-				count = ll - pos;
-			} else {
-				ntfs_error(vol->sb, "Cannot perform write to "
-						"inode 0x%lx, attribute type "
-						"0x%x, because extending the "
-						"allocation failed (error "
-						"code %i).", vi->i_ino,
-						(unsigned)
-						le32_to_cpu(ni->type), err);
-				return err;
-			}
-		}
-	}
-	written = 0;
-	/*
-	 * If the write starts beyond the initialized size, extend it up to the
-	 * beginning of the write and initialize all non-sparse space between
-	 * the old initialized size and the new one.  This automatically also
-	 * increments the vfs inode->i_size to keep it above or equal to the
-	 * initialized_size.
-	 */
-	read_lock_irqsave(&ni->size_lock, flags);
-	ll = ni->initialized_size;
-	read_unlock_irqrestore(&ni->size_lock, flags);
-	if (pos > ll) {
-		err = ntfs_attr_extend_initialized(ni, pos);
-		if (err < 0) {
-			ntfs_error(vol->sb, "Cannot perform write to inode "
-					"0x%lx, attribute type 0x%x, because "
-					"extending the initialized size "
-					"failed (error code %i).", vi->i_ino,
-					(unsigned)le32_to_cpu(ni->type), err);
-			status = err;
-			goto err_out;
-		}
-	}
 	/*
 	 * Determine the number of pages per cluster for non-resident
 	 * attributes.
@@ -1937,10 +1791,7 @@ static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
 	nr_pages = 1;
 	if (vol->cluster_size > PAGE_CACHE_SIZE && NInoNonResident(ni))
 		nr_pages = vol->cluster_size >> PAGE_CACHE_SHIFT;
-	/* Finally, perform the actual write. */
 	last_vcn = -1;
-	if (likely(nr_segs == 1))
-		buf = iov->iov_base;
 	do {
 		VCN vcn;
 		pgoff_t idx, start_idx;
@@ -1965,10 +1816,10 @@ static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
 						vol->cluster_size_bits, false);
 				up_read(&ni->runlist.lock);
 				if (unlikely(lcn < LCN_HOLE)) {
-					status = -EIO;
 					if (lcn == LCN_ENOMEM)
 						status = -ENOMEM;
-					else
+					else {
+						status = -EIO;
 						ntfs_error(vol->sb, "Cannot "
 							"perform write to "
 							"inode 0x%lx, "
@@ -1977,6 +1828,7 @@ static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
 							"is corrupt.",
 							vi->i_ino, (unsigned)
 							le32_to_cpu(ni->type));
+					}
 					break;
 				}
 				if (lcn == LCN_HOLE) {
@@ -1989,8 +1841,9 @@ static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
 				}
 			}
 		}
-		if (bytes > count)
-			bytes = count;
+		if (bytes > iov_iter_count(i))
+			bytes = iov_iter_count(i);
+again:
 		/*
 		 * Bring in the user page(s) that we will copy from _first_.
 		 * Otherwise there is a nasty deadlock on copying from the same
@@ -1999,10 +1852,10 @@ static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
 		 * pages being swapped out between us bringing them into memory
 		 * and doing the actual copying.
 		 */
-		if (likely(nr_segs == 1))
-			ntfs_fault_in_pages_readable(buf, bytes);
-		else
-			ntfs_fault_in_pages_readable_iovec(iov, iov_ofs, bytes);
+		if (unlikely(iov_iter_fault_in_multipages_readable(i, bytes))) {
+			status = -EFAULT;
+			break;
+		}
 		/* Get and lock @do_pages starting at index @start_idx. */
 		status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
 				pages, &cached_page);
@@ -2018,56 +1871,57 @@ static ssize_t ntfs_file_buffered_write(struct kiocb *iocb,
 			status = ntfs_prepare_pages_for_non_resident_write(
 					pages, do_pages, pos, bytes);
 			if (unlikely(status)) {
-				loff_t i_size;
-
 				do {
 					unlock_page(pages[--do_pages]);
 					page_cache_release(pages[do_pages]);
 				} while (do_pages);
-				/*
-				 * The write preparation may have instantiated
-				 * allocated space outside i_size.  Trim this
-				 * off again.  We can ignore any errors in this
-				 * case as we will just be waisting a bit of
-				 * allocated space, which is not a disaster.
-				 */
-				i_size = i_size_read(vi);
-				if (pos + bytes > i_size) {
-					ntfs_write_failed(mapping, pos + bytes);
-				}
 				break;
 			}
 		}
 		u = (pos >> PAGE_CACHE_SHIFT) - pages[0]->index;
-		if (likely(nr_segs == 1)) {
-			copied = ntfs_copy_from_user(pages + u, do_pages - u,
-					ofs, buf, bytes);
-			buf += copied;
-		} else
-			copied = ntfs_copy_from_user_iovec(pages + u,
-					do_pages - u, ofs, &iov, &iov_ofs,
-					bytes);
+		copied = ntfs_copy_from_user_iter(pages + u, do_pages - u, ofs,
+					i, bytes);
 		ntfs_flush_dcache_pages(pages + u, do_pages - u);
-		status = ntfs_commit_pages_after_write(pages, do_pages, pos,
-				bytes);
-		if (likely(!status)) {
-			written += copied;
-			count -= copied;
-			pos += copied;
-			if (unlikely(copied != bytes))
-				status = -EFAULT;
+		status = 0;
+		if (likely(copied == bytes)) {
+			status = ntfs_commit_pages_after_write(pages, do_pages,
+					pos, bytes);
+			if (!status)
+				status = bytes;
 		}
 		do {
 			unlock_page(pages[--do_pages]);
 			page_cache_release(pages[do_pages]);
 		} while (do_pages);
-		if (unlikely(status))
+		if (unlikely(status < 0))
 			break;
-		balance_dirty_pages_ratelimited(mapping);
+		copied = status;
 		cond_resched();
-	} while (count);
-err_out:
-	*ppos = pos;
+		if (unlikely(!copied)) {
+			size_t sc;
+
+			/*
+			 * We failed to copy anything.  Fall back to single
+			 * segment length write.
+			 *
+			 * This is needed to avoid possible livelock in the
+			 * case that all segments in the iov cannot be copied
+			 * at once without a pagefault.
+			 */
+			sc = iov_iter_single_seg_count(i);
+			if (bytes > sc)
+				bytes = sc;
+			goto again;
+		}
+		iov_iter_advance(i, copied);
+		pos += copied;
+		written += copied;
+		balance_dirty_pages_ratelimited(mapping);
+		if (fatal_signal_pending(current)) {
+			status = -EINTR;
+			break;
+		}
+	} while (iov_iter_count(i));
 	if (cached_page)
 		page_cache_release(cached_page);
 	ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
@@ -2077,59 +1931,56 @@ err_out:
 }
 
 /**
- * ntfs_file_aio_write_nolock -
+ * ntfs_file_write_iter_nolock - write data to a file
+ * @iocb:	IO state structure (file, offset, etc.)
+ * @from:	iov_iter with data to write
+ *
+ * Basically the same as __generic_file_write_iter() except that it ends
+ * up calling ntfs_perform_write() instead of generic_perform_write() and that
+ * O_DIRECT is not implemented.
  */
-static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
-		const struct iovec *iov, unsigned long nr_segs, loff_t *ppos)
+static ssize_t ntfs_file_write_iter_nolock(struct kiocb *iocb,
+		struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
-	struct address_space *mapping = file->f_mapping;
-	struct inode *inode = mapping->host;
-	loff_t pos;
-	size_t count;		/* after file limit checks */
-	ssize_t written, err;
+	loff_t pos = iocb->ki_pos;
+	ssize_t written = 0;
+	ssize_t err;
+	size_t count = iov_iter_count(from);
 
-	count = iov_length(iov, nr_segs);
-	pos = *ppos;
-	/* We can write back this queue in page reclaim. */
-	current->backing_dev_info = inode_to_bdi(inode);
-	written = 0;
-	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
-	if (err)
-		goto out;
-	if (!count)
-		goto out;
-	err = file_remove_suid(file);
-	if (err)
-		goto out;
-	err = file_update_time(file);
-	if (err)
-		goto out;
-	written = ntfs_file_buffered_write(iocb, iov, nr_segs, pos, ppos,
-			count);
-out:
+	err = ntfs_prepare_file_for_write(file, &pos, &count);
+	if (count && !err) {
+		iov_iter_truncate(from, count);
+		written = ntfs_perform_write(file, from, pos);
+		if (likely(written >= 0))
+			iocb->ki_pos = pos + written;
+	}
 	current->backing_dev_info = NULL;
 	return written ? written : err;
 }
 
 /**
- * ntfs_file_aio_write -
+ * ntfs_file_write_iter - simple wrapper for ntfs_file_write_iter_nolock()
+ * @iocb:	IO state structure
+ * @from:	iov_iter with data to write
+ *
+ * Basically the same as generic_file_write_iter() except that it ends up
+ * calling ntfs_file_write_iter_nolock() instead of
+ * __generic_file_write_iter().
  */
-static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
-		unsigned long nr_segs, loff_t pos)
+static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
-	struct address_space *mapping = file->f_mapping;
-	struct inode *inode = mapping->host;
+	struct inode *vi = file_inode(file);
 	ssize_t ret;
 
-	BUG_ON(iocb->ki_pos != pos);
-
-	mutex_lock(&inode->i_mutex);
-	ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
-	mutex_unlock(&inode->i_mutex);
+	mutex_lock(&vi->i_mutex);
+	ret = ntfs_file_write_iter_nolock(iocb, from);
+	mutex_unlock(&vi->i_mutex);
 	if (ret > 0) {
-		int err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+		ssize_t err;
+
+		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
 		if (err < 0)
 			ret = err;
 	}
@@ -2197,37 +2048,17 @@ static int ntfs_file_fsync(struct file *filp, loff_t start, loff_t end,
 #endif /* NTFS_RW */
 
 const struct file_operations ntfs_file_ops = {
-	.llseek		= generic_file_llseek,	 /* Seek inside file. */
-	.read		= new_sync_read,	 /* Read from file. */
-	.read_iter	= generic_file_read_iter, /* Async read from file. */
+	.llseek		= generic_file_llseek,
+	.read		= new_sync_read,
+	.read_iter	= generic_file_read_iter,
 #ifdef NTFS_RW
-	.write		= do_sync_write,	 /* Write to file. */
-	.aio_write	= ntfs_file_aio_write,	 /* Async write to file. */
-	/*.release	= ,*/			 /* Last file is closed.  See
-						    fs/ext2/file.c::
-						    ext2_release_file() for
-						    how to use this to discard
-						    preallocated space for
-						    write opened files. */
-	.fsync		= ntfs_file_fsync,	 /* Sync a file to disk. */
-	/*.aio_fsync	= ,*/			 /* Sync all outstanding async
-						    i/o operations on a
-						    kiocb. */
+	.write		= new_sync_write,
+	.write_iter	= ntfs_file_write_iter,
+	.fsync		= ntfs_file_fsync,
 #endif /* NTFS_RW */
-	/*.ioctl	= ,*/			 /* Perform function on the
-						    mounted filesystem. */
-	.mmap		= generic_file_mmap,	 /* Mmap file. */
-	.open		= ntfs_file_open,	 /* Open file. */
-	.splice_read	= generic_file_splice_read /* Zero-copy data send with
-						    the data source being on
-						    the ntfs partition.  We do
-						    not need to care about the
-						    data destination. */
-	/*.sendpage	= ,*/			 /* Zero-copy data send with
-						    the data destination being
-						    on the ntfs partition.  We
-						    do not need to care about
-						    the data source. */
+	.mmap		= generic_file_mmap,
+	.open		= ntfs_file_open,
+	.splice_read	= generic_file_splice_read,
 };
 
 const struct inode_operations ntfs_file_inode_ops = {