/**
* ntfs_extent_inode_open - load an extent inode and attach it to its base
* @base_ni: base ntfs inode
* @mref: mft reference of the extent inode to load (in little endian)
*
* First check if the extent inode @mref is already attached to the base ntfs
* inode @base_ni, and if so, return a pointer to the attached extent inode.
*
* If the extent inode is not already attached to the base inode, allocate an
* ntfs_inode structure and initialize it for the given inode @mref. @mref
* specifies the inode number / mft record to read, including the sequence
* number, which can be 0 if no sequence number checking is to be performed.
*
* Then, allocate a buffer for the mft record, read the mft record from the
* volume @base_ni->vol, and attach it to the ntfs_inode structure (->mrec).
* The mft record is mst deprotected and sanity checked for validity and we
* abort if deprotection or checks fail.
*
* Finally attach the ntfs inode to its base inode @base_ni and return a
* pointer to the ntfs_inode structure on success or NULL on error, with errno
* set to the error code.
*
* Note, extent inodes are never closed directly. They are automatically
* disposed off by the closing of the base inode.
*/
ntfs_inode *ntfs_extent_inode_open(ntfs_inode *base_ni, const MFT_REF mref)
{
u64 mft_no = MREF_LE(mref);
ntfs_inode *ni = NULL;
ntfs_inode **extent_nis;
int i;
if (!base_ni) {
errno = EINVAL;
ntfs_log_perror("%s", __FUNCTION__);
return NULL;
}
ntfs_log_enter("Opening extent inode %lld (base mft record %lld).\n",
(unsigned long long)mft_no,
(unsigned long long)base_ni->mft_no);
/* Is the extent inode already open and attached to the base inode? */
if (base_ni->nr_extents > 0) {
extent_nis = base_ni->extent_nis;
for (i = 0; i < base_ni->nr_extents; i++) {
u16 seq_no;
ni = extent_nis[i];
if (mft_no != ni->mft_no)
continue;
/* Verify the sequence number if given. */
seq_no = MSEQNO_LE(mref);
if (seq_no && seq_no != le16_to_cpu(
ni->mrec->sequence_number)) {
errno = EIO;
ntfs_log_perror("Found stale extent mft "
"reference mft=%lld",
(long long)ni->mft_no);
goto out;
}
goto out;
}
}
/* Wasn't there, we need to load the extent inode. */
ni = __ntfs_inode_allocate(base_ni->vol);
if (!ni)
goto out;
if (ntfs_file_record_read(base_ni->vol, le64_to_cpu(mref), &ni->mrec, NULL))
goto err_out;
ni->mft_no = mft_no;
ni->nr_extents = -1;
ni->base_ni = base_ni;
/* Attach extent inode to base inode, reallocating memory if needed. */
if (!(base_ni->nr_extents & 3)) {
i = (base_ni->nr_extents + 4) * sizeof(ntfs_inode *);
extent_nis = ntfs_malloc(i);
if (!extent_nis)
goto err_out;
if (base_ni->nr_extents) {
memcpy(extent_nis, base_ni->extent_nis,
i - 4 * sizeof(ntfs_inode *));
free(base_ni->extent_nis);
}
base_ni->extent_nis = extent_nis;
}
base_ni->extent_nis[base_ni->nr_extents++] = ni;
out:
ntfs_log_leave("\n");
return ni;
err_out:
__ntfs_inode_release(ni);
ni = NULL;
goto out;
}
/**
* map_extent_mft_record - load an extent inode and attach it to its base
* @base_ni: base ntfs inode
* @mref: mft reference of the extent inode to load (in little endian)
* @ntfs_ino: on successful return, pointer to the ntfs_inode structure
*
* Load the extent mft record @mref and attach it to its base inode @base_ni.
* Return the mapped extent mft record if IS_ERR(result) is false. Otherwise
* PTR_ERR(result) gives the negative error code.
*
* On successful return, @ntfs_ino contains a pointer to the ntfs_inode
* structure of the mapped extent inode.
*/
MFT_RECORD *map_extent_mft_record(ntfs_inode *base_ni, MFT_REF mref,
ntfs_inode **ntfs_ino)
{
MFT_RECORD *m;
ntfs_inode *ni = NULL;
ntfs_inode **extent_nis = NULL;
int i;
unsigned long mft_no = MREF_LE(mref);
u16 seq_no = MSEQNO_LE(mref);
BOOL destroy_ni = FALSE;
ntfs_debug("Mapping extent mft record 0x%lx (base mft record 0x%lx).",
mft_no, base_ni->mft_no);
/* Make sure the base ntfs inode doesn't go away. */
atomic_inc(&base_ni->count);
/*
* Check if this extent inode has already been added to the base inode,
* in which case just return it. If not found, add it to the base
* inode before returning it.
*/
down(&base_ni->extent_lock);
if (base_ni->nr_extents > 0) {
extent_nis = base_ni->ext.extent_ntfs_inos;
for (i = 0; i < base_ni->nr_extents; i++) {
if (mft_no != extent_nis[i]->mft_no)
continue;
ni = extent_nis[i];
/* Make sure the ntfs inode doesn't go away. */
atomic_inc(&ni->count);
break;
}
}
if (likely(ni != NULL)) {
up(&base_ni->extent_lock);
atomic_dec(&base_ni->count);
/* We found the record; just have to map and return it. */
m = map_mft_record(ni);
/* map_mft_record() has incremented this on success. */
atomic_dec(&ni->count);
if (likely(!IS_ERR(m))) {
/* Verify the sequence number. */
if (likely(le16_to_cpu(m->sequence_number) == seq_no)) {
ntfs_debug("Done 1.");
*ntfs_ino = ni;
return m;
}
unmap_mft_record(ni);
ntfs_error(base_ni->vol->sb, "Found stale extent mft "
"reference! Corrupt file system. "
"Run chkdsk.");
return ERR_PTR(-EIO);
}
map_err_out:
ntfs_error(base_ni->vol->sb, "Failed to map extent "
"mft record, error code %ld.", -PTR_ERR(m));
return m;
}
/* Record wasn't there. Get a new ntfs inode and initialize it. */
ni = ntfs_new_extent_inode(base_ni->vol->sb, mft_no);
if (unlikely(!ni)) {
up(&base_ni->extent_lock);
atomic_dec(&base_ni->count);
return ERR_PTR(-ENOMEM);
}
ni->vol = base_ni->vol;
ni->seq_no = seq_no;
ni->nr_extents = -1;
ni->ext.base_ntfs_ino = base_ni;
/* Now map the record. */
m = map_mft_record(ni);
if (unlikely(IS_ERR(m))) {
up(&base_ni->extent_lock);
atomic_dec(&base_ni->count);
ntfs_clear_extent_inode(ni);
goto map_err_out;
}
/* Verify the sequence number. */
if (unlikely(le16_to_cpu(m->sequence_number) != seq_no)) {
ntfs_error(base_ni->vol->sb, "Found stale extent mft "
"reference! Corrupt file system. Run chkdsk.");
destroy_ni = TRUE;
m = ERR_PTR(-EIO);
goto unm_err_out;
}
/* Attach extent inode to base inode, reallocating memory if needed. */
if (!(base_ni->nr_extents & 3)) {
ntfs_inode **tmp;
int new_size = (base_ni->nr_extents + 4) * sizeof(ntfs_inode *);
tmp = (ntfs_inode **)kmalloc(new_size, GFP_NOFS);
if (unlikely(!tmp)) {
ntfs_error(base_ni->vol->sb, "Failed to allocate "
"internal buffer.");
destroy_ni = TRUE;
m = ERR_PTR(-ENOMEM);
goto unm_err_out;
}
if (base_ni->ext.extent_ntfs_inos) {
memcpy(tmp, base_ni->ext.extent_ntfs_inos, new_size -
4 * sizeof(ntfs_inode *));
kfree(base_ni->ext.extent_ntfs_inos);
}
base_ni->ext.extent_ntfs_inos = tmp;
}
base_ni->ext.extent_ntfs_inos[base_ni->nr_extents++] = ni;
up(&base_ni->extent_lock);
atomic_dec(&base_ni->count);
ntfs_debug("Done 2.");
*ntfs_ino = ni;
return m;
unm_err_out:
unmap_mft_record(ni);
up(&base_ni->extent_lock);
atomic_dec(&base_ni->count);
/*
* If the extent inode was not attached to the base inode we need to
* release it or we will leak memory.
*/
if (destroy_ni)
ntfs_clear_extent_inode(ni);
return m;
}
