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 = {