fs/ntfs3: Refactoring attr_set_size to restore after errors

Added comments to code
Added two undo labels for restoring after errors
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/attrib.c

@@ -173,7 +173,6 @@ int attr_allocate_clusters(struct ntfs_sb_info *sbi, struct runs_tree *run,
 {
 	int err;
 	CLST flen, vcn0 = vcn, pre = pre_alloc ? *pre_alloc : 0;
-	struct wnd_bitmap *wnd = &sbi->used.bitmap;
 	size_t cnt = run->count;
 
 	for (;;) {
@@ -196,9 +195,7 @@ int attr_allocate_clusters(struct ntfs_sb_info *sbi, struct runs_tree *run,
 		/* Add new fragment into run storage. */
 		if (!run_add_entry(run, vcn, lcn, flen, opt == ALLOCATE_MFT)) {
 			/* Undo last 'ntfs_look_for_free_space' */
-			down_write_nested(&wnd->rw_lock, BITMAP_MUTEX_CLUSTERS);
-			wnd_set_free(wnd, lcn, flen);
-			up_write(&wnd->rw_lock);
+			mark_as_free_ex(sbi, lcn, len, false);
 			err = -ENOMEM;
 			goto out;
 		}
@@ -419,40 +416,44 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 	struct mft_inode *mi, *mi_b;
 	CLST alen, vcn, lcn, new_alen, old_alen, svcn, evcn;
 	CLST next_svcn, pre_alloc = -1, done = 0;
-	bool is_ext;
+	bool is_ext, is_bad = false;
 	u32 align;
 	struct MFT_REC *rec;
 
 again:
+	alen = 0;
 	le_b = NULL;
 	attr_b = ni_find_attr(ni, NULL, &le_b, type, name, name_len, NULL,
 			      &mi_b);
 	if (!attr_b) {
 		err = -ENOENT;
-		goto out;
+		goto bad_inode;
 	}
 
 	if (!attr_b->non_res) {
 		err = attr_set_size_res(ni, attr_b, le_b, mi_b, new_size, run,
 					&attr_b);
-		if (err || !attr_b->non_res)
-			goto out;
+		if (err)
+			return err;
+
+		/* Return if file is still resident. */
+		if (!attr_b->non_res)
+			goto ok1;
 
 		/* Layout of records may be changed, so do a full search. */
 		goto again;
 	}
 
 	is_ext = is_attr_ext(attr_b);
-
-again_1:
 	align = sbi->cluster_size;
-
 	if (is_ext)
 		align <<= attr_b->nres.c_unit;
 
 	old_valid = le64_to_cpu(attr_b->nres.valid_size);
 	old_size = le64_to_cpu(attr_b->nres.data_size);
 	old_alloc = le64_to_cpu(attr_b->nres.alloc_size);
+
+again_1:
 	old_alen = old_alloc >> cluster_bits;
 
 	new_alloc = (new_size + align - 1) & ~(u64)(align - 1);
@@ -475,24 +476,27 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 		mi = mi_b;
 	} else if (!le_b) {
 		err = -EINVAL;
-		goto out;
+		goto bad_inode;
 	} else {
 		le = le_b;
 		attr = ni_find_attr(ni, attr_b, &le, type, name, name_len, &vcn,
 				    &mi);
 		if (!attr) {
 			err = -EINVAL;
-			goto out;
+			goto bad_inode;
 		}
 
 next_le_1:
 		svcn = le64_to_cpu(attr->nres.svcn);
 		evcn = le64_to_cpu(attr->nres.evcn);
 	}
-
+	/*
+	 * Here we have:
+	 * attr,mi,le - last attribute segment (containing 'vcn').
+	 * attr_b,mi_b,le_b - base (primary) attribute segment.
+	 */
 next_le:
 	rec = mi->mrec;
-
 	err = attr_load_runs(attr, ni, run, NULL);
 	if (err)
 		goto out;
@@ -507,6 +511,13 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 			goto ok;
 		}
 
+		/*
+		 * Add clusters. In simple case we have to:
+		 *  - allocate space (vcn, lcn, len)
+		 *  - update packed run in 'mi'
+		 *  - update attr->nres.evcn
+		 *  - update attr_b->nres.data_size/attr_b->nres.alloc_size
+		 */
 		to_allocate = new_alen - old_alen;
 add_alloc_in_same_attr_seg:
 		lcn = 0;
@@ -520,9 +531,11 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 			pre_alloc = 0;
 			if (type == ATTR_DATA && !name_len &&
 			    sbi->options->prealloc) {
-				CLST new_alen2 = bytes_to_cluster(
-					sbi, get_pre_allocated(new_size));
-				pre_alloc = new_alen2 - new_alen;
+				pre_alloc =
+					bytes_to_cluster(
+						sbi,
+						get_pre_allocated(new_size)) -
+					new_alen;
 			}
 
 			/* Get the last LCN to allocate from. */
@@ -580,7 +593,7 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 pack_runs:
 		err = mi_pack_runs(mi, attr, run, vcn - svcn);
 		if (err)
-			goto out;
+			goto undo_1;
 
 		next_svcn = le64_to_cpu(attr->nres.evcn) + 1;
 		new_alloc_tmp = (u64)next_svcn << cluster_bits;
@@ -614,7 +627,7 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 		if (type == ATTR_LIST) {
 			err = ni_expand_list(ni);
 			if (err)
-				goto out;
+				goto undo_2;
 			if (next_svcn < vcn)
 				goto pack_runs;
 
@@ -624,8 +637,9 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 
 		if (!ni->attr_list.size) {
 			err = ni_create_attr_list(ni);
+			/* In case of error layout of records is not changed. */
 			if (err)
-				goto out;
+				goto undo_2;
 			/* Layout of records is changed. */
 		}
 
@@ -638,47 +652,56 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 		err = ni_insert_nonresident(ni, type, name, name_len, run,
 					    next_svcn, vcn - next_svcn,
 					    attr_b->flags, &attr, &mi, NULL);
-		if (err)
-			goto out;
-
-		if (!is_mft)
-			run_truncate_head(run, evcn + 1);
 
-		svcn = le64_to_cpu(attr->nres.svcn);
-		evcn = le64_to_cpu(attr->nres.evcn);
-
-		le_b = NULL;
 		/*
 		 * Layout of records maybe changed.
 		 * Find base attribute to update.
 		 */
+		le_b = NULL;
 		attr_b = ni_find_attr(ni, NULL, &le_b, type, name, name_len,
 				      NULL, &mi_b);
 		if (!attr_b) {
-			err = -ENOENT;
-			goto out;
+			err = -EINVAL;
+			goto bad_inode;
 		}
 
-		attr_b->nres.alloc_size = cpu_to_le64((u64)vcn << cluster_bits);
-		attr_b->nres.data_size = attr_b->nres.alloc_size;
-		attr_b->nres.valid_size = attr_b->nres.alloc_size;
+		if (err) {
+			/* ni_insert_nonresident failed. */
+			attr = NULL;
+			goto undo_2;
+		}
+
+		if (!is_mft)
+			run_truncate_head(run, evcn + 1);
+
+		svcn = le64_to_cpu(attr->nres.svcn);
+		evcn = le64_to_cpu(attr->nres.evcn);
+
+		/*
+		 * Attribute is in consistency state.
+		 * Save this point to restore to if next steps fail.
+		 */
+		old_valid = old_size = old_alloc = (u64)vcn << cluster_bits;
+		attr_b->nres.valid_size = attr_b->nres.data_size =
+			attr_b->nres.alloc_size = cpu_to_le64(old_size);
 		mi_b->dirty = true;
 		goto again_1;
 	}
 
 	if (new_size != old_size ||
 	    (new_alloc != old_alloc && !keep_prealloc)) {
+		/*
+		 * Truncate clusters. In simple case we have to:
+		 *  - update packed run in 'mi'
+		 *  - update attr->nres.evcn
+		 *  - update attr_b->nres.data_size/attr_b->nres.alloc_size
+		 *  - mark and trim clusters as free (vcn, lcn, len)
+		 */
+		CLST dlen = 0;
+
 		vcn = max(svcn, new_alen);
 		new_alloc_tmp = (u64)vcn << cluster_bits;
 
-		alen = 0;
-		err = run_deallocate_ex(sbi, run, vcn, evcn - vcn + 1, &alen,
-					true);
-		if (err)
-			goto out;
-
-		run_truncate(run, vcn);
-
 		if (vcn > svcn) {
 			err = mi_pack_runs(mi, attr, run, vcn - svcn);
 			if (err)
@@ -697,7 +720,7 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 
 			if (!al_remove_le(ni, le)) {
 				err = -EINVAL;
-				goto out;
+				goto bad_inode;
 			}
 
 			le = (struct ATTR_LIST_ENTRY *)((u8 *)le - le_sz);
@@ -723,12 +746,20 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 				attr_b->nres.valid_size =
 					attr_b->nres.alloc_size;
 		}
+		mi_b->dirty = true;
 
-		if (is_ext)
+		err = run_deallocate_ex(sbi, run, vcn, evcn - vcn + 1, &dlen,
+					true);
+		if (err)
+			goto out;
+
+		if (is_ext) {
+			/* dlen - really deallocated clusters. */
 			le64_sub_cpu(&attr_b->nres.total_size,
-				     ((u64)alen << cluster_bits));
+				     ((u64)dlen << cluster_bits));
+		}
 
-		mi_b->dirty = true;
+		run_truncate(run, vcn);
 
 		if (new_alloc_tmp <= new_alloc)
 			goto ok;
@@ -747,7 +778,7 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 		if (le->type != type || le->name_len != name_len ||
 		    memcmp(le_name(le), name, name_len * sizeof(short))) {
 			err = -EINVAL;
-			goto out;
+			goto bad_inode;
 		}
 
 		err = ni_load_mi(ni, le, &mi);
@@ -757,7 +788,7 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 		attr = mi_find_attr(mi, NULL, type, name, name_len, &le->id);
 		if (!attr) {
 			err = -EINVAL;
-			goto out;
+			goto bad_inode;
 		}
 		goto next_le_1;
 	}
@@ -772,13 +803,13 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 		}
 	}
 
-out:
-	if (!err && attr_b && ret)
+ok1:
+	if (ret)
 		*ret = attr_b;
 
 	/* Update inode_set_bytes. */
-	if (!err && ((type == ATTR_DATA && !name_len) ||
-		     (type == ATTR_ALLOC && name == I30_NAME))) {
+	if (((type == ATTR_DATA && !name_len) ||
+	     (type == ATTR_ALLOC && name == I30_NAME))) {
 		bool dirty = false;
 
 		if (ni->vfs_inode.i_size != new_size) {
@@ -786,7 +817,7 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 			dirty = true;
 		}
 
-		if (attr_b && attr_b->non_res) {
+		if (attr_b->non_res) {
 			new_alloc = le64_to_cpu(attr_b->nres.alloc_size);
 			if (inode_get_bytes(&ni->vfs_inode) != new_alloc) {
 				inode_set_bytes(&ni->vfs_inode, new_alloc);
@@ -800,6 +831,47 @@ int attr_set_size(struct ntfs_inode *ni, enum ATTR_TYPE type,
 		}
 	}
 
+	return 0;
+
+undo_2:
+	vcn -= alen;
+	attr_b->nres.data_size = cpu_to_le64(old_size);
+	attr_b->nres.valid_size = cpu_to_le64(old_valid);
+	attr_b->nres.alloc_size = cpu_to_le64(old_alloc);
+
+	/* Restore 'attr' and 'mi'. */
+	if (attr)
+		goto restore_run;
+
+	if (le64_to_cpu(attr_b->nres.svcn) <= svcn &&
+	    svcn <= le64_to_cpu(attr_b->nres.evcn)) {
+		attr = attr_b;
+		le = le_b;
+		mi = mi_b;
+	} else if (!le_b) {
+		err = -EINVAL;
+		goto bad_inode;
+	} else {
+		le = le_b;
+		attr = ni_find_attr(ni, attr_b, &le, type, name, name_len,
+				    &svcn, &mi);
+		if (!attr)
+			goto bad_inode;
+	}
+
+restore_run:
+	if (mi_pack_runs(mi, attr, run, evcn - svcn + 1))
+		is_bad = true;
+
+undo_1:
+	run_deallocate_ex(sbi, run, vcn, alen, NULL, false);
+
+	run_truncate(run, vcn);
+out:
+	if (is_bad) {
+bad_inode:
+		_ntfs_bad_inode(&ni->vfs_inode);
+	}
 	return err;
 }