1 files changed, 544 insertions, 86 deletions

diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 1ff7f90a18b0..cd0f9e740b14 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -1,7 +1,7 @@
 /**
  * attrib.c - NTFS attribute operations.  Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2004 Anton Altaparmakov
+ * Copyright (c) 2001-2005 Anton Altaparmakov
  * Copyright (c) 2002 Richard Russon
  *
  * This program/include file is free software; you can redistribute it and/or
@@ -21,88 +21,217 @@
  */
 
 #include <linux/buffer_head.h>
+#include <linux/swap.h>
 
 #include "attrib.h"
 #include "debug.h"
 #include "layout.h"
+#include "lcnalloc.h"
+#include "malloc.h"
 #include "mft.h"
 #include "ntfs.h"
 #include "types.h"
 
 /**
- * ntfs_map_runlist - map (a part of) a runlist of an ntfs inode
+ * ntfs_map_runlist_nolock - map (a part of) a runlist of an ntfs inode
  * @ni:         ntfs inode for which to map (part of) a runlist
  * @vcn:        map runlist part containing this vcn
  *
  * Map the part of a runlist containing the @vcn of the ntfs inode @ni.
  *
- * Return 0 on success and -errno on error.
+ * Return 0 on success and -errno on error.  There is one special error code
+ * which is not an error as such.  This is -ENOENT.  It means that @vcn is out
+ * of bounds of the runlist.
  *
- * Locking: - The runlist must be unlocked on entry and is unlocked on return.
- *          - This function takes the lock for writing and modifies the runlist.
+ * Locking: - The runlist must be locked for writing.
+ *          - This function modifies the runlist.
  */
-int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
+int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn)
 {
+        VCN end_vcn;
         ntfs_inode *base_ni;
+        MFT_RECORD *m;
+        ATTR_RECORD *a;
         ntfs_attr_search_ctx *ctx;
-        MFT_RECORD *mrec;
+        runlist_element *rl;
         int err = 0;
 
         ntfs_debug("Mapping runlist part containing vcn 0x%llx.",
                         (unsigned long long)vcn);
-
         if (!NInoAttr(ni))
                 base_ni = ni;
         else
                 base_ni = ni->ext.base_ntfs_ino;
-
-        mrec = map_mft_record(base_ni);
-        if (IS_ERR(mrec))
-                return PTR_ERR(mrec);
-        ctx = ntfs_attr_get_search_ctx(base_ni, mrec);
+        m = map_mft_record(base_ni);
+        if (IS_ERR(m))
+                return PTR_ERR(m);
+        ctx = ntfs_attr_get_search_ctx(base_ni, m);
         if (unlikely(!ctx)) {
                 err = -ENOMEM;
                 goto err_out;
         }
         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
                         CASE_SENSITIVE, vcn, NULL, 0, ctx);
-        if (unlikely(err))
-                goto put_err_out;
+        if (unlikely(err)) {
+                if (err == -ENOENT)
+                        err = -EIO;
+                goto err_out;
+        }
+        a = ctx->attr;
+        /*
+         * Only decompress the mapping pairs if @vcn is inside it.  Otherwise
+         * we get into problems when we try to map an out of bounds vcn because
+         * we then try to map the already mapped runlist fragment and
+         * ntfs_mapping_pairs_decompress() fails.
+         */
+        end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn) + 1;
+        if (unlikely(!a->data.non_resident.lowest_vcn && end_vcn <= 1))
+                end_vcn = ni->allocated_size >> ni->vol->cluster_size_bits;
+        if (unlikely(vcn >= end_vcn)) {
+                err = -ENOENT;
+                goto err_out;
+        }
+        rl = ntfs_mapping_pairs_decompress(ni->vol, a, ni->runlist.rl);
+        if (IS_ERR(rl))
+                err = PTR_ERR(rl);
+        else
+                ni->runlist.rl = rl;
+err_out:
+        if (likely(ctx))
+                ntfs_attr_put_search_ctx(ctx);
+        unmap_mft_record(base_ni);
+        return err;
+}
+
+/**
+ * ntfs_map_runlist - map (a part of) a runlist of an ntfs inode
+ * @ni:         ntfs inode for which to map (part of) a runlist
+ * @vcn:        map runlist part containing this vcn
+ *
+ * Map the part of a runlist containing the @vcn of the ntfs inode @ni.
+ *
+ * Return 0 on success and -errno on error.  There is one special error code
+ * which is not an error as such.  This is -ENOENT.  It means that @vcn is out
+ * of bounds of the runlist.
+ *
+ * Locking: - The runlist must be unlocked on entry and is unlocked on return.
+ *          - This function takes the runlist lock for writing and modifies the
+ *            runlist.
+ */
+int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
+{
+        int err = 0;
 
         down_write(&ni->runlist.lock);
         /* Make sure someone else didn't do the work while we were sleeping. */
         if (likely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) <=
-                        LCN_RL_NOT_MAPPED)) {
-                runlist_element *rl;
+                        LCN_RL_NOT_MAPPED))
+                err = ntfs_map_runlist_nolock(ni, vcn);
+        up_write(&ni->runlist.lock);
+        return err;
+}
 
-                rl = ntfs_mapping_pairs_decompress(ni->vol, ctx->attr,
-                                ni->runlist.rl);
-                if (IS_ERR(rl))
-                        err = PTR_ERR(rl);
-                else
-                        ni->runlist.rl = rl;
+/**
+ * ntfs_attr_vcn_to_lcn_nolock - convert a vcn into a lcn given an ntfs inode
+ * @ni:                 ntfs inode of the attribute whose runlist to search
+ * @vcn:                vcn to convert
+ * @write_locked:       true if the runlist is locked for writing
+ *
+ * Find the virtual cluster number @vcn in the runlist of the ntfs attribute
+ * described by the ntfs inode @ni and return the corresponding logical cluster
+ * number (lcn).
+ *
+ * If the @vcn is not mapped yet, the attempt is made to map the attribute
+ * extent containing the @vcn and the vcn to lcn conversion is retried.
+ *
+ * If @write_locked is true the caller has locked the runlist for writing and
+ * if false for reading.
+ *
+ * Since lcns must be >= 0, we use negative return codes with special meaning:
+ *
+ * Return code  Meaning / Description
+ * ==========================================
+ *  LCN_HOLE    Hole / not allocated on disk.
+ *  LCN_ENOENT  There is no such vcn in the runlist, i.e. @vcn is out of bounds.
+ *  LCN_ENOMEM  Not enough memory to map runlist.
+ *  LCN_EIO     Critical error (runlist/file is corrupt, i/o error, etc).
+ *
+ * Locking: - The runlist must be locked on entry and is left locked on return.
+ *          - If @write_locked is FALSE, i.e. the runlist is locked for reading,
+ *            the lock may be dropped inside the function so you cannot rely on
+ *            the runlist still being the same when this function returns.
+ */
+LCN ntfs_attr_vcn_to_lcn_nolock(ntfs_inode *ni, const VCN vcn,
+                const BOOL write_locked)
+{
+        LCN lcn;
+        BOOL is_retry = FALSE;
+
+        ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
+                        ni->mft_no, (unsigned long long)vcn,
+                        write_locked ? "write" : "read");
+        BUG_ON(!ni);
+        BUG_ON(!NInoNonResident(ni));
+        BUG_ON(vcn < 0);
+retry_remap:
+        /* Convert vcn to lcn.  If that fails map the runlist and retry once. */
+        lcn = ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn);
+        if (likely(lcn >= LCN_HOLE)) {
+                ntfs_debug("Done, lcn 0x%llx.", (long long)lcn);
+                return lcn;
         }
-        up_write(&ni->runlist.lock);
+        if (lcn != LCN_RL_NOT_MAPPED) {
+                if (lcn != LCN_ENOENT)
+                        lcn = LCN_EIO;
+        } else if (!is_retry) {
+                int err;
 
-put_err_out:
-        ntfs_attr_put_search_ctx(ctx);
-err_out:
-        unmap_mft_record(base_ni);
-        return err;
+                if (!write_locked) {
+                        up_read(&ni->runlist.lock);
+                        down_write(&ni->runlist.lock);
+                        if (unlikely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) !=
+                                        LCN_RL_NOT_MAPPED)) {
+                                up_write(&ni->runlist.lock);
+                                down_read(&ni->runlist.lock);
+                                goto retry_remap;
+                        }
+                }
+                err = ntfs_map_runlist_nolock(ni, vcn);
+                if (!write_locked) {
+                        up_write(&ni->runlist.lock);
+                        down_read(&ni->runlist.lock);
+                }
+                if (likely(!err)) {
+                        is_retry = TRUE;
+                        goto retry_remap;
+                }
+                if (err == -ENOENT)
+                        lcn = LCN_ENOENT;
+                else if (err == -ENOMEM)
+                        lcn = LCN_ENOMEM;
+                else
+                        lcn = LCN_EIO;
+        }
+        if (lcn != LCN_ENOENT)
+                ntfs_error(ni->vol->sb, "Failed with error code %lli.",
+                                (long long)lcn);
+        return lcn;
 }
 
 /**
- * ntfs_find_vcn - find a vcn in the runlist described by an ntfs inode
- * @ni:         ntfs inode describing the runlist to search
- * @vcn:        vcn to find
- * @need_write: if false, lock for reading and if true, lock for writing
+ * ntfs_attr_find_vcn_nolock - find a vcn in the runlist of an ntfs inode
+ * @ni:                 ntfs inode describing the runlist to search
+ * @vcn:                vcn to find
+ * @write_locked:       true if the runlist is locked for writing
  *
  * Find the virtual cluster number @vcn in the runlist described by the ntfs
  * inode @ni and return the address of the runlist element containing the @vcn.
- * The runlist is left locked and the caller has to unlock it.  If @need_write
- * is true, the runlist is locked for writing and if @need_write is false, the
- * runlist is locked for reading.  In the error case, the runlist is not left
- * locked.
+ *
+ * If the @vcn is not mapped yet, the attempt is made to map the attribute
+ * extent containing the @vcn and the vcn to lcn conversion is retried.
+ *
+ * If @write_locked is true the caller has locked the runlist for writing and
+ * if false for reading.
  *
  * Note you need to distinguish between the lcn of the returned runlist element
  * being >= 0 and LCN_HOLE.  In the later case you have to return zeroes on
@@ -118,34 +247,29 @@ err_out:
  *      -ENOMEM - Not enough memory to map runlist.
  *      -EIO    - Critical error (runlist/file is corrupt, i/o error, etc).
  *
- * Locking: - The runlist must be unlocked on entry.
- *          - On failing return, the runlist is unlocked.
- *          - On successful return, the runlist is locked.  If @need_write us
- *            true, it is locked for writing.  Otherwise is is locked for
- *            reading.
+ * Locking: - The runlist must be locked on entry and is left locked on return.
+ *          - If @write_locked is FALSE, i.e. the runlist is locked for reading,
+ *            the lock may be dropped inside the function so you cannot rely on
+ *            the runlist still being the same when this function returns.
  */
-runlist_element *ntfs_find_vcn(ntfs_inode *ni, const VCN vcn,
-                const BOOL need_write)
+runlist_element *ntfs_attr_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
+                const BOOL write_locked)
 {
         runlist_element *rl;
         int err = 0;
         BOOL is_retry = FALSE;
 
-        ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, lock for %sing.",
+        ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
                         ni->mft_no, (unsigned long long)vcn,
-                        !need_write ? "read" : "writ");
+                        write_locked ? "write" : "read");
         BUG_ON(!ni);
         BUG_ON(!NInoNonResident(ni));
         BUG_ON(vcn < 0);
-lock_retry_remap:
-        if (!need_write)
-                down_read(&ni->runlist.lock);
-        else
-                down_write(&ni->runlist.lock);
+retry_remap:
         rl = ni->runlist.rl;
         if (likely(rl && vcn >= rl[0].vcn)) {
                 while (likely(rl->length)) {
-                        if (likely(vcn < rl[1].vcn)) {
+                        if (unlikely(vcn < rl[1].vcn)) {
                                 if (likely(rl->lcn >= LCN_HOLE)) {
                                         ntfs_debug("Done.");
                                         return rl;
@@ -161,30 +285,41 @@ lock_retry_remap:
                                 err = -EIO;
                 }
         }
-        if (!need_write)
-                up_read(&ni->runlist.lock);
-        else
-                up_write(&ni->runlist.lock);
         if (!err && !is_retry) {
                 /*
                  * The @vcn is in an unmapped region, map the runlist and
                  * retry.
                  */
-                err = ntfs_map_runlist(ni, vcn);
+                if (!write_locked) {
+                        up_read(&ni->runlist.lock);
+                        down_write(&ni->runlist.lock);
+                        if (unlikely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) !=
+                                        LCN_RL_NOT_MAPPED)) {
+                                up_write(&ni->runlist.lock);
+                                down_read(&ni->runlist.lock);
+                                goto retry_remap;
+                        }
+                }
+                err = ntfs_map_runlist_nolock(ni, vcn);
+                if (!write_locked) {
+                        up_write(&ni->runlist.lock);
+                        down_read(&ni->runlist.lock);
+                }
                 if (likely(!err)) {
                         is_retry = TRUE;
-                        goto lock_retry_remap;
+                        goto retry_remap;
                 }
                 /*
-                 * -EINVAL and -ENOENT coming from a failed mapping attempt are
-                 * equivalent to i/o errors for us as they should not happen in
-                 * our code paths.
+                 * -EINVAL coming from a failed mapping attempt is equivalent
+                 * to i/o error for us as it should not happen in our code
+                 * paths.
                  */
-                if (err == -EINVAL || err == -ENOENT)
+                if (err == -EINVAL)
                         err = -EIO;
         } else if (!err)
                 err = -EIO;
-        ntfs_error(ni->vol->sb, "Failed with error code %i.", err);
+        if (err != -ENOENT)
+                ntfs_error(ni->vol->sb, "Failed with error code %i.", err);
         return ERR_PTR(err);
 }
 
@@ -870,15 +1005,14 @@ int ntfs_attr_lookup(const ATTR_TYPE type, const ntfschar *name,
 static inline void ntfs_attr_init_search_ctx(ntfs_attr_search_ctx *ctx,
                 ntfs_inode *ni, MFT_RECORD *mrec)
 {
-        ctx->mrec = mrec;
-        /* Sanity checks are performed elsewhere. */
-        ctx->attr = (ATTR_RECORD*)((u8*)mrec + le16_to_cpu(mrec->attrs_offset));
-        ctx->is_first = TRUE;
-        ctx->ntfs_ino = ni;
-        ctx->al_entry = NULL;
-        ctx->base_ntfs_ino = NULL;
-        ctx->base_mrec = NULL;
-        ctx->base_attr = NULL;
+        *ctx = (ntfs_attr_search_ctx) {
+                .mrec = mrec,
+                /* Sanity checks are performed elsewhere. */
+                .attr = (ATTR_RECORD*)((u8*)mrec +
+                                le16_to_cpu(mrec->attrs_offset)),
+                .is_first = TRUE,
+                .ntfs_ino = ni,
+        };
 }
 
 /**
@@ -945,6 +1079,8 @@ void ntfs_attr_put_search_ctx(ntfs_attr_search_ctx *ctx)
         return;
 }
 
+#ifdef NTFS_RW
+
 /**
  * ntfs_attr_find_in_attrdef - find an attribute in the $AttrDef system file
  * @vol:        ntfs volume to which the attribute belongs
@@ -1024,27 +1160,21 @@ int ntfs_attr_size_bounds_check(const ntfs_volume *vol, const ATTR_TYPE type,
  * Check whether the attribute of @type on the ntfs volume @vol is allowed to
  * be non-resident.  This information is obtained from $AttrDef system file.
  *
- * Return 0 if the attribute is allowed to be non-resident, -EPERM if not, or
+ * Return 0 if the attribute is allowed to be non-resident, -EPERM if not, and
  * -ENOENT if the attribute is not listed in $AttrDef.
  */
 int ntfs_attr_can_be_non_resident(const ntfs_volume *vol, const ATTR_TYPE type)
 {
         ATTR_DEF *ad;
 
-        /*
-         * $DATA is always allowed to be non-resident even if $AttrDef does not
-         * specify this in the flags of the $DATA attribute definition record.
-         */
-        if (type == AT_DATA)
-                return 0;
         /* Find the attribute definition record in $AttrDef. */
         ad = ntfs_attr_find_in_attrdef(vol, type);
         if (unlikely(!ad))
                 return -ENOENT;
         /* Check the flags and return the result. */
-        if (ad->flags & CAN_BE_NON_RESIDENT)
-                return 0;
-        return -EPERM;
+        if (ad->flags & ATTR_DEF_RESIDENT)
+                return -EPERM;
+        return 0;
 }
 
 /**
@@ -1067,9 +1197,9 @@ int ntfs_attr_can_be_non_resident(const ntfs_volume *vol, const ATTR_TYPE type)
  */
 int ntfs_attr_can_be_resident(const ntfs_volume *vol, const ATTR_TYPE type)
 {
-        if (type != AT_INDEX_ALLOCATION && type != AT_EA)
-                return 0;
-        return -EPERM;
+        if (type == AT_INDEX_ALLOCATION || type == AT_EA)
+                return -EPERM;
+        return 0;
 }
 
 /**
@@ -1117,6 +1247,328 @@ int ntfs_attr_record_resize(MFT_RECORD *m, ATTR_RECORD *a, u32 new_size)
 }
 
 /**
+ * ntfs_attr_make_non_resident - convert a resident to a non-resident attribute
+ * @ni:         ntfs inode describing the attribute to convert
+ *
+ * Convert the resident ntfs attribute described by the ntfs inode @ni to a
+ * non-resident one.
+ *
+ * Return 0 on success and -errno on error.  The following error return codes
+ * are defined:
+ *      -EPERM  - The attribute is not allowed to be non-resident.
+ *      -ENOMEM - Not enough memory.
+ *      -ENOSPC - Not enough disk space.
+ *      -EINVAL - Attribute not defined on the volume.
+ *      -EIO    - I/o error or other error.
+ * Note that -ENOSPC is also returned in the case that there is not enough
+ * space in the mft record to do the conversion.  This can happen when the mft
+ * record is already very full.  The caller is responsible for trying to make
+ * space in the mft record and trying again.  FIXME: Do we need a separate
+ * error return code for this kind of -ENOSPC or is it always worth trying
+ * again in case the attribute may then fit in a resident state so no need to
+ * make it non-resident at all?  Ho-hum...  (AIA)
+ *
+ * NOTE to self: No changes in the attribute list are required to move from
+ *               a resident to a non-resident attribute.
+ *
+ * Locking: - The caller must hold i_sem on the inode.
+ */
+int ntfs_attr_make_non_resident(ntfs_inode *ni)
+{
+        s64 new_size;
+        struct inode *vi = VFS_I(ni);
+        ntfs_volume *vol = ni->vol;
+        ntfs_inode *base_ni;
+        MFT_RECORD *m;
+        ATTR_RECORD *a;
+        ntfs_attr_search_ctx *ctx;
+        struct page *page;
+        runlist_element *rl;
+        u8 *kaddr;
+        unsigned long flags;
+        int mp_size, mp_ofs, name_ofs, arec_size, err, err2;
+        u32 attr_size;
+        u8 old_res_attr_flags;
+
+        /* Check that the attribute is allowed to be non-resident. */
+        err = ntfs_attr_can_be_non_resident(vol, ni->type);
+        if (unlikely(err)) {
+                if (err == -EPERM)
+                        ntfs_debug("Attribute is not allowed to be "
+                                        "non-resident.");
+                else
+                        ntfs_debug("Attribute not defined on the NTFS "
+                                        "volume!");
+                return err;
+        }
+        /*
+         * The size needs to be aligned to a cluster boundary for allocation
+         * purposes.
+         */
+        new_size = (i_size_read(vi) + vol->cluster_size - 1) &
+                        ~(vol->cluster_size - 1);
+        if (new_size > 0) {
+                runlist_element *rl2;
+
+                /*
+                 * Will need the page later and since the page lock nests
+                 * outside all ntfs locks, we need to get the page now.
+                 */
+                page = find_or_create_page(vi->i_mapping, 0,
+                                mapping_gfp_mask(vi->i_mapping));
+                if (unlikely(!page))
+                        return -ENOMEM;
+                /* Start by allocating clusters to hold the attribute value. */
+                rl = ntfs_cluster_alloc(vol, 0, new_size >>
+                                vol->cluster_size_bits, -1, DATA_ZONE);
+                if (IS_ERR(rl)) {
+                        err = PTR_ERR(rl);
+                        ntfs_debug("Failed to allocate cluster%s, error code "
+                                        "%i.", (new_size >>
+                                        vol->cluster_size_bits) > 1 ? "s" : "",
+                                        err);
+                        goto page_err_out;
+                }
+                /* Change the runlist terminator to LCN_ENOENT. */
+                rl2 = rl;
+                while (rl2->length)
+                        rl2++;
+                BUG_ON(rl2->lcn != LCN_RL_NOT_MAPPED);
+                rl2->lcn = LCN_ENOENT;
+        } else {
+                rl = NULL;
+                page = NULL;
+        }
+        /* Determine the size of the mapping pairs array. */
+        mp_size = ntfs_get_size_for_mapping_pairs(vol, rl, 0, -1);
+        if (unlikely(mp_size < 0)) {
+                err = mp_size;
+                ntfs_debug("Failed to get size for mapping pairs array, error "
+                                "code %i.", err);
+                goto rl_err_out;
+        }
+        down_write(&ni->runlist.lock);
+        if (!NInoAttr(ni))
+                base_ni = ni;
+        else
+                base_ni = ni->ext.base_ntfs_ino;
+        m = map_mft_record(base_ni);
+        if (IS_ERR(m)) {
+                err = PTR_ERR(m);
+                m = NULL;
+                ctx = NULL;
+                goto err_out;
+        }
+        ctx = ntfs_attr_get_search_ctx(base_ni, m);
+        if (unlikely(!ctx)) {
+                err = -ENOMEM;
+                goto err_out;
+        }
+        err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                        CASE_SENSITIVE, 0, NULL, 0, ctx);
+        if (unlikely(err)) {
+                if (err == -ENOENT)
+                        err = -EIO;
+                goto err_out;
+        }
+        m = ctx->mrec;
+        a = ctx->attr;
+        BUG_ON(NInoNonResident(ni));
+        BUG_ON(a->non_resident);
+        /*
+         * Calculate new offsets for the name and the mapping pairs array.
+         * We assume the attribute is not compressed or sparse.
+         */
+        name_ofs = (offsetof(ATTR_REC,
+                        data.non_resident.compressed_size) + 7) & ~7;
+        mp_ofs = (name_ofs + a->name_length * sizeof(ntfschar) + 7) & ~7;
+        /*
+         * Determine the size of the resident part of the now non-resident
+         * attribute record.
+         */
+        arec_size = (mp_ofs + mp_size + 7) & ~7;
+        /*
+         * If the page is not uptodate bring it uptodate by copying from the
+         * attribute value.
+         */
+        attr_size = le32_to_cpu(a->data.resident.value_length);
+        BUG_ON(attr_size != i_size_read(vi));
+        if (page && !PageUptodate(page)) {
+                kaddr = kmap_atomic(page, KM_USER0);
+                memcpy(kaddr, (u8*)a +
+                                le16_to_cpu(a->data.resident.value_offset),
+                                attr_size);
+                memset(kaddr + attr_size, 0, PAGE_CACHE_SIZE - attr_size);
+                kunmap_atomic(kaddr, KM_USER0);
+                flush_dcache_page(page);
+                SetPageUptodate(page);
+        }
+        /* Backup the attribute flag. */
+        old_res_attr_flags = a->data.resident.flags;
+        /* Resize the resident part of the attribute record. */
+        err = ntfs_attr_record_resize(m, a, arec_size);
+        if (unlikely(err))
+                goto err_out;
+        /*
+         * Convert the resident part of the attribute record to describe a
+         * non-resident attribute.
+         */
+        a->non_resident = 1;
+        /* Move the attribute name if it exists and update the offset. */
+        if (a->name_length)
+                memmove((u8*)a + name_ofs, (u8*)a + le16_to_cpu(a->name_offset),
+                                a->name_length * sizeof(ntfschar));
+        a->name_offset = cpu_to_le16(name_ofs);
+        /*
+         * FIXME: For now just clear all of these as we do not support them
+         * when writing.
+         */
+        a->flags &= cpu_to_le16(0xffff & ~le16_to_cpu(ATTR_IS_SPARSE |
+                        ATTR_IS_ENCRYPTED | ATTR_COMPRESSION_MASK));
+        /* Setup the fields specific to non-resident attributes. */
+        a->data.non_resident.lowest_vcn = 0;
+        a->data.non_resident.highest_vcn = cpu_to_sle64((new_size - 1) >>
+                        vol->cluster_size_bits);
+        a->data.non_resident.mapping_pairs_offset = cpu_to_le16(mp_ofs);
+        a->data.non_resident.compression_unit = 0;
+        memset(&a->data.non_resident.reserved, 0,
+                        sizeof(a->data.non_resident.reserved));
+        a->data.non_resident.allocated_size = cpu_to_sle64(new_size);
+        a->data.non_resident.data_size =
+                        a->data.non_resident.initialized_size =
+                        cpu_to_sle64(attr_size);
+        /* Generate the mapping pairs array into the attribute record. */
+        err = ntfs_mapping_pairs_build(vol, (u8*)a + mp_ofs,
+                        arec_size - mp_ofs, rl, 0, -1, NULL);
+        if (unlikely(err)) {
+                ntfs_debug("Failed to build mapping pairs, error code %i.",
+                                err);
+                goto undo_err_out;
+        }
+        /* Setup the in-memory attribute structure to be non-resident. */
+        /*
+         * FIXME: For now just clear all of these as we do not support them
+         * when writing.
+         */
+        NInoClearSparse(ni);
+        NInoClearEncrypted(ni);
+        NInoClearCompressed(ni);
+        ni->runlist.rl = rl;
+        write_lock_irqsave(&ni->size_lock, flags);
+        ni->allocated_size = new_size;
+        write_unlock_irqrestore(&ni->size_lock, flags);
+        /*
+         * This needs to be last since the address space operations ->readpage
+         * and ->writepage can run concurrently with us as they are not
+         * serialized on i_sem.  Note, we are not allowed to fail once we flip
+         * this switch, which is another reason to do this last.
+         */
+        NInoSetNonResident(ni);
+        /* Mark the mft record dirty, so it gets written back. */
+        flush_dcache_mft_record_page(ctx->ntfs_ino);
+        mark_mft_record_dirty(ctx->ntfs_ino);
+        ntfs_attr_put_search_ctx(ctx);
+        unmap_mft_record(base_ni);
+        up_write(&ni->runlist.lock);
+        if (page) {
+                set_page_dirty(page);
+                unlock_page(page);
+                mark_page_accessed(page);
+                page_cache_release(page);
+        }
+        ntfs_debug("Done.");
+        return 0;
+undo_err_out:
+        /* Convert the attribute back into a resident attribute. */
+        a->non_resident = 0;
+        /* Move the attribute name if it exists and update the offset. */
+        name_ofs = (offsetof(ATTR_RECORD, data.resident.reserved) +
+                        sizeof(a->data.resident.reserved) + 7) & ~7;
+        if (a->name_length)
+                memmove((u8*)a + name_ofs, (u8*)a + le16_to_cpu(a->name_offset),
+                                a->name_length * sizeof(ntfschar));
+        mp_ofs = (name_ofs + a->name_length * sizeof(ntfschar) + 7) & ~7;
+        a->name_offset = cpu_to_le16(name_ofs);
+        arec_size = (mp_ofs + attr_size + 7) & ~7;
+        /* Resize the resident part of the attribute record. */
+        err2 = ntfs_attr_record_resize(m, a, arec_size);
+        if (unlikely(err2)) {
+                /*
+                 * This cannot happen (well if memory corruption is at work it
+                 * could happen in theory), but deal with it as well as we can.
+                 * If the old size is too small, truncate the attribute,
+                 * otherwise simply give it a larger allocated size.
+                 * FIXME: Should check whether chkdsk complains when the
+                 * allocated size is much bigger than the resident value size.
+                 */
+                arec_size = le32_to_cpu(a->length);
+                if ((mp_ofs + attr_size) > arec_size) {
+                        err2 = attr_size;
+                        attr_size = arec_size - mp_ofs;
+                        ntfs_error(vol->sb, "Failed to undo partial resident "
+                                        "to non-resident attribute "
+                                        "conversion.  Truncating inode 0x%lx, "
+                                        "attribute type 0x%x from %i bytes to "
+                                        "%i bytes to maintain metadata "
+                                        "consistency.  THIS MEANS YOU ARE "
+                                        "LOSING %i BYTES DATA FROM THIS %s.",
+                                        vi->i_ino,
+                                        (unsigned)le32_to_cpu(ni->type),
+                                        err2, attr_size, err2 - attr_size,
+                                        ((ni->type == AT_DATA) &&
+                                        !ni->name_len) ? "FILE": "ATTRIBUTE");
+                        write_lock_irqsave(&ni->size_lock, flags);
+                        ni->initialized_size = attr_size;
+                        i_size_write(vi, attr_size);
+                        write_unlock_irqrestore(&ni->size_lock, flags);
+                }
+        }
+        /* Setup the fields specific to resident attributes. */
+        a->data.resident.value_length = cpu_to_le32(attr_size);
+        a->data.resident.value_offset = cpu_to_le16(mp_ofs);
+        a->data.resident.flags = old_res_attr_flags;
+        memset(&a->data.resident.reserved, 0,
+                        sizeof(a->data.resident.reserved));
+        /* Copy the data from the page back to the attribute value. */
+        if (page) {
+                kaddr = kmap_atomic(page, KM_USER0);
+                memcpy((u8*)a + mp_ofs, kaddr, attr_size);
+                kunmap_atomic(kaddr, KM_USER0);
+        }
+        /* Setup the allocated size in the ntfs inode in case it changed. */
+        write_lock_irqsave(&ni->size_lock, flags);
+        ni->allocated_size = arec_size - mp_ofs;
+        write_unlock_irqrestore(&ni->size_lock, flags);
+        /* Mark the mft record dirty, so it gets written back. */
+        flush_dcache_mft_record_page(ctx->ntfs_ino);
+        mark_mft_record_dirty(ctx->ntfs_ino);
+err_out:
+        if (ctx)
+                ntfs_attr_put_search_ctx(ctx);
+        if (m)
+                unmap_mft_record(base_ni);
+        ni->runlist.rl = NULL;
+        up_write(&ni->runlist.lock);
+rl_err_out:
+        if (rl) {
+                if (ntfs_cluster_free_from_rl(vol, rl) < 0) {
+                        ntfs_error(vol->sb, "Failed to release allocated "
+                                        "cluster(s) in error code path.  Run "
+                                        "chkdsk to recover the lost "
+                                        "cluster(s).");
+                        NVolSetErrors(vol);
+                }
+                ntfs_free(rl);
+page_err_out:
+                unlock_page(page);
+                page_cache_release(page);
+        }
+        if (err == -EINVAL)
+                err = -EIO;
+        return err;
+}
+
+/**
  * ntfs_attr_set - fill (a part of) an attribute with a byte
  * @ni:         ntfs inode describing the attribute to fill
  * @ofs:        offset inside the attribute at which to start to fill
@@ -1127,6 +1579,10 @@ int ntfs_attr_record_resize(MFT_RECORD *m, ATTR_RECORD *a, u32 new_size)
  * byte offset @ofs inside the attribute with the constant byte @val.
  *
  * This function is effectively like memset() applied to an ntfs attribute.
+ * Note thie function actually only operates on the page cache pages belonging
+ * to the ntfs attribute and it marks them dirty after doing the memset().
+ * Thus it relies on the vm dirty page write code paths to cause the modified
+ * pages to be written to the mft record/disk.
  *
  * Return 0 on success and -errno on error.  An error code of -ESPIPE means
  * that @ofs + @cnt were outside the end of the attribute and no write was
@@ -1155,7 +1611,7 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
         end = ofs + cnt;
         end_ofs = end & ~PAGE_CACHE_MASK;
         /* If the end is outside the inode size return -ESPIPE. */
-        if (unlikely(end > VFS_I(ni)->i_size)) {
+        if (unlikely(end > i_size_read(VFS_I(ni)))) {
                 ntfs_error(vol->sb, "Request exceeds end of attribute.");
                 return -ESPIPE;
         }
@@ -1256,3 +1712,5 @@ done:
         ntfs_debug("Done.");
         return 0;
 }
+
+#endif /* NTFS_RW */