/**
* 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
+ * @ni: ntfs inode describing the runlist to search
+ * @vcn: vcn to find
+ * @ctx: active attribute search context if present or NULL if not
*
* 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.
* 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.
+ * If @ctx is specified, it is an active search context of @ni and its base mft
+ * record. This is needed when ntfs_attr_find_vcn_nolock() encounters unmapped
+ * runlist fragments and allows their mapping. If you do not have the mft
+ * record mapped, you can specify @ctx as NULL and ntfs_attr_find_vcn_nolock()
+ * will perform the necessary mapping and unmapping.
*
+ * Note, ntfs_attr_find_vcn_nolock() saves the state of @ctx on entry and
+ * restores it before returning. Thus, @ctx will be left pointing to the same
+ * attribute on return as on entry. However, the actual pointers in @ctx may
+ * point to different memory locations on return, so you must remember to reset
+ * any cached pointers from the @ctx, i.e. after the call to
+ * ntfs_attr_find_vcn_nolock(), you will probably want to do:
+ * m = ctx->mrec;
+ * a = ctx->attr;
+ * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
+ * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
* 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
* read and allocate clusters on write.
* -ENOMEM - Not enough memory to map runlist.
* -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.
+ * WARNING: If @ctx is supplied, regardless of whether success or failure is
+ * returned, you need to check IS_ERR(@ctx->mrec) and if TRUE the @ctx
+ * is no longer valid, i.e. you need to either call
+ * ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
+ * In that case PTR_ERR(@ctx->mrec) will give you the error code for
+ * why the mapping of the old inode failed.
+ *
+ * Locking: - The runlist described by @ni must be locked for writing on entry
+ * and is locked on return. Note the runlist may be modified when
+ * needed runlist fragments need to be mapped.
+ * - If @ctx is NULL, the base mft record of @ni must not be mapped on
+ * entry and it will be left unmapped on return.
+ * - If @ctx is not NULL, the base mft record must be mapped on entry
+ * and it will be left mapped on return.
*/
runlist_element *ntfs_attr_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
- const BOOL write_locked)
+ ntfs_attr_search_ctx *ctx)
{
unsigned long flags;
runlist_element *rl;
int err = 0;
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");
+ ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, with%s ctx.",
+ ni->mft_no, (unsigned long long)vcn, ctx ? "" : "out");
BUG_ON(!ni);
BUG_ON(!NInoNonResident(ni));
BUG_ON(vcn < 0);
}
if (!err && !is_retry) {
/*
- * The @vcn is in an unmapped region, map the runlist and
- * retry.
+ * If the search context is invalid we cannot map the unmapped
+ * region.
*/
- 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);
+ if (IS_ERR(ctx->mrec))
+ err = PTR_ERR(ctx->mrec);
+ else {
+ /*
+ * The @vcn is in an unmapped region, map the runlist
+ * and retry.
+ */
+ err = ntfs_map_runlist_nolock(ni, vcn, ctx);
+ if (likely(!err)) {
+ is_retry = TRUE;
goto retry_remap;
}
}
- err = ntfs_map_runlist_nolock(ni, vcn, NULL);
- if (!write_locked) {
- up_write(&ni->runlist.lock);
- down_read(&ni->runlist.lock);
- }
- if (likely(!err)) {
- is_retry = TRUE;
- goto retry_remap;
- }
- /*
- * -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 = -EIO;
} else if (!err)
ntfs_inode *base_ni;
ntfs_debug("Entering.");
+ BUG_ON(IS_ERR(ctx->mrec));
if (ctx->base_ntfs_ino)
base_ni = ctx->base_ntfs_ino;
else
ntfs_volume *vol = ni->vol;
struct inode *mft_vi = vol->mft_ino;
struct page *page;
- unsigned long index, ofs, end_index;
+ unsigned long index, end_index;
+ unsigned ofs;
BUG_ON(ni->page);
/*
ll = mftbmp_ni->allocated_size;
read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
rl = ntfs_attr_find_vcn_nolock(mftbmp_ni,
- (ll - 1) >> vol->cluster_size_bits, TRUE);
+ (ll - 1) >> vol->cluster_size_bits, NULL);
if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
up_write(&mftbmp_ni->runlist.lock);
ntfs_error(vol->sb, "Failed to determine last allocated "
ll = mft_ni->allocated_size;
read_unlock_irqrestore(&mft_ni->size_lock, flags);
rl = ntfs_attr_find_vcn_nolock(mft_ni,
- (ll - 1) >> vol->cluster_size_bits, TRUE);
+ (ll - 1) >> vol->cluster_size_bits, NULL);
if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
up_write(&mft_ni->runlist.lock);
ntfs_error(vol->sb, "Failed to determine last allocated "
git.openpandora.org / pandora-kernel.git / commitdiff