NTFS: Add fs/ntfs/attrib.[hc]::ntfs_attr_make_non_resident().

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

3 files changed, 303 insertions, 0 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 7507a56a4921..71680a92b4d6 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -97,6 +97,7 @@ ToDo/Notes:
           whether someone else did not already do the work we wanted to do.
         - Rename fs/ntfs/attrib.c::ntfs_find_vcn_nolock() to
           ntfs_attr_find_vcn_nolock() and update all callers.
+        - Add fs/ntfs/attrib.[hc]::ntfs_attr_make_non_resident().
 
 2.1.22 - Many bug and race fixes and error handling improvements.
 
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 6de5e04e97a2..3b9de4040216 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -25,6 +25,8 @@
 #include "attrib.h"
 #include "debug.h"
 #include "layout.h"
+#include "lcnalloc.h"
+#include "malloc.h"
 #include "mft.h"
 #include "ntfs.h"
 #include "types.h"
@@ -1227,6 +1229,304 @@ 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 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) {
+                /*
+                 * 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.\n", (new_size >>
+                                        vol->cluster_size_bits) > 1 ? "s" : "",
+                                        err);
+                        goto page_err_out;
+                }
+        } else {
+                rl = NULL;
+                page = NULL;
+        }
+        /* Determine the size of the mapping pairs array. */
+        mp_size = ntfs_get_size_for_mapping_pairs(vol, rl, 0);
+        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;
+        /* Setup the in-memory attribute structure to be non-resident. */
+        NInoSetNonResident(ni);
+        ni->runlist.rl = rl;
+        write_lock_irqsave(&ni->size_lock, flags);
+        ni->allocated_size = new_size;
+        write_unlock_irqrestore(&ni->size_lock, flags);
+        /*
+         * FIXME: For now just clear all of these as we do not support them
+         * when writing.
+         */
+        NInoClearCompressed(ni);
+        NInoClearSparse(ni);
+        NInoClearEncrypted(ni);
+        /*
+         * 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);
+        /* Update the flags to match the in-memory ones. */
+        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, NULL);
+        if (unlikely(err)) {
+                ntfs_debug("Failed to build mapping pairs, error code %i.",
+                                err);
+                goto undo_err_out;
+        }
+        /* 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);
+                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);
+        }
+        /* Finally setup the ntfs inode appropriately. */
+        write_lock_irqsave(&ni->size_lock, flags);
+        ni->allocated_size = arec_size - mp_ofs;
+        write_unlock_irqrestore(&ni->size_lock, flags);
+        NInoClearNonResident(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);
+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_free(rl);
+                        ntfs_error(vol->sb, "Failed to release allocated "
+                                        "cluster(s) in error code path.  Run "
+                                        "chkdsk to recover the lost "
+                                        "cluster(s).");
+                        NVolSetErrors(vol);
+                }
+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
diff --git a/fs/ntfs/attrib.h b/fs/ntfs/attrib.h
index e0a50f1ca76f..d73385198336 100644
--- a/fs/ntfs/attrib.h
+++ b/fs/ntfs/attrib.h
@@ -98,6 +98,8 @@ extern int ntfs_attr_can_be_resident(const ntfs_volume *vol,
 
 extern int ntfs_attr_record_resize(MFT_RECORD *m, ATTR_RECORD *a, u32 new_size);
 
+extern int ntfs_attr_make_non_resident(ntfs_inode *ni);
+
 extern int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt,
                 const u8 val);