fs/ntfs3: Restore correct state after ENOSPC in attr_data_get_block

Added new function ntfs_check_for_free_space.
Added undo mechanism in attr_data_get_block.
Fixes xfstest generic/083

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/attrib.c

@@ -891,8 +891,10 @@ int attr_data_get_block(struct ntfs_inode *ni, CLST vcn, CLST clen, CLST *lcn,
 	struct ATTR_LIST_ENTRY *le, *le_b;
 	struct mft_inode *mi, *mi_b;
 	CLST hint, svcn, to_alloc, evcn1, next_svcn, asize, end, vcn0, alen;
+	CLST alloc, evcn;
 	unsigned fr;
-	u64 total_size;
+	u64 total_size, total_size0;
+	int step = 0;
 
 	if (new)
 		*new = false;
@@ -932,7 +934,12 @@ int attr_data_get_block(struct ntfs_inode *ni, CLST vcn, CLST clen, CLST *lcn,
 
 	asize = le64_to_cpu(attr_b->nres.alloc_size) >> cluster_bits;
 	if (vcn >= asize) {
-		err = -EINVAL;
+		if (new) {
+			err = -EINVAL;
+		} else {
+			*len = 1;
+			*lcn = SPARSE_LCN;
+		}
 		goto out;
 	}
 
@@ -1036,10 +1043,12 @@ int attr_data_get_block(struct ntfs_inode *ni, CLST vcn, CLST clen, CLST *lcn,
 	if (err)
 		goto out;
 	*new = true;
+	step = 1;
 
 	end = vcn + alen;
-	total_size = le64_to_cpu(attr_b->nres.total_size) +
+	/* Save 'total_size0' to restore if error. */
-		     ((u64)alen << cluster_bits);
+	total_size0 = le64_to_cpu(attr_b->nres.total_size);
+	total_size = total_size0 + ((u64)alen << cluster_bits);
 
 	if (vcn != vcn0) {
 		if (!run_lookup_entry(run, vcn0, lcn, len, NULL)) {
@@ -1081,7 +1090,7 @@ repack:
 		if (!ni->attr_list.size) {
 			err = ni_create_attr_list(ni);
 			if (err)
-				goto out;
+				goto undo1;
 			/* Layout of records is changed. */
 			le_b = NULL;
 			attr_b = ni_find_attr(ni, NULL, &le_b, ATTR_DATA, NULL,
@@ -1098,67 +1107,83 @@ repack:
 		}
 	}
 
+	/* 
+	 * The code below may require additional cluster (to extend attribute list)
+	 * and / or one MFT record 
+	 * It is too complex to undo operations if -ENOSPC occurs deep inside 
+	 * in 'ni_insert_nonresident'.
+	 * Return in advance -ENOSPC here if there are no free cluster and no free MFT.
+	 */
+	if (!ntfs_check_for_free_space(sbi, 1, 1)) {
+		/* Undo step 1. */
+		err = -ENOSPC;
+		goto undo1;
+	}
+
+	step = 2;
 	svcn = evcn1;
 
 	/* Estimate next attribute. */
 	attr = ni_find_attr(ni, attr, &le, ATTR_DATA, NULL, 0, &svcn, &mi);
 
-	if (attr) {
+	if (!attr) {
-		CLST alloc = bytes_to_cluster(
+		/* Insert new attribute segment. */
-			sbi, le64_to_cpu(attr_b->nres.alloc_size));
+		goto ins_ext;
-		CLST evcn = le64_to_cpu(attr->nres.evcn);
+	}
 
-		if (end < next_svcn)
+	/* Try to update existed attribute segment. */
-			end = next_svcn;
+	alloc = bytes_to_cluster(sbi, le64_to_cpu(attr_b->nres.alloc_size));
-		while (end > evcn) {
+	evcn = le64_to_cpu(attr->nres.evcn);
-			/* Remove segment [svcn : evcn). */
-			mi_remove_attr(NULL, mi, attr);
 
-			if (!al_remove_le(ni, le)) {
+	if (end < next_svcn)
-				err = -EINVAL;
+		end = next_svcn;
-				goto out;
+	while (end > evcn) {
-			}
+		/* Remove segment [svcn : evcn). */
+		mi_remove_attr(NULL, mi, attr);
 
-			if (evcn + 1 >= alloc) {
+		if (!al_remove_le(ni, le)) {
-				/* Last attribute segment. */
+			err = -EINVAL;
-				evcn1 = evcn + 1;
+			goto out;
-				goto ins_ext;
-			}
-
-			if (ni_load_mi(ni, le, &mi)) {
-				attr = NULL;
-				goto out;
-			}
-
-			attr = mi_find_attr(mi, NULL, ATTR_DATA, NULL, 0,
-					    &le->id);
-			if (!attr) {
-				err = -EINVAL;
-				goto out;
-			}
-			svcn = le64_to_cpu(attr->nres.svcn);
-			evcn = le64_to_cpu(attr->nres.evcn);
 		}
 
-		if (end < svcn)
+		if (evcn + 1 >= alloc) {
-			end = svcn;
+			/* Last attribute segment. */
+			evcn1 = evcn + 1;
+			goto ins_ext;
+		}
 
-		err = attr_load_runs(attr, ni, run, &end);
+		if (ni_load_mi(ni, le, &mi)) {
-		if (err)
+			attr = NULL;
 			goto out;
+		}
 
-		evcn1 = evcn + 1;
+		attr = mi_find_attr(mi, NULL, ATTR_DATA, NULL, 0, &le->id);
-		attr->nres.svcn = cpu_to_le64(next_svcn);
+		if (!attr) {
-		err = mi_pack_runs(mi, attr, run, evcn1 - next_svcn);
+			err = -EINVAL;
-		if (err)
 			goto out;
-
+		}
-		le->vcn = cpu_to_le64(next_svcn);
+		svcn = le64_to_cpu(attr->nres.svcn);
-		ni->attr_list.dirty = true;
+		evcn = le64_to_cpu(attr->nres.evcn);
-		mi->dirty = true;
-
-		next_svcn = le64_to_cpu(attr->nres.evcn) + 1;
 	}
+
+	if (end < svcn)
+		end = svcn;
+
+	err = attr_load_runs(attr, ni, run, &end);
+	if (err)
+		goto out;
+
+	evcn1 = evcn + 1;
+	attr->nres.svcn = cpu_to_le64(next_svcn);
+	err = mi_pack_runs(mi, attr, run, evcn1 - next_svcn);
+	if (err)
+		goto out;
+
+	le->vcn = cpu_to_le64(next_svcn);
+	ni->attr_list.dirty = true;
+	mi->dirty = true;
+	next_svcn = le64_to_cpu(attr->nres.evcn) + 1;
+
 ins_ext:
 	if (evcn1 > next_svcn) {
 		err = ni_insert_nonresident(ni, ATTR_DATA, NULL, 0, run,
@@ -1170,10 +1195,26 @@ ins_ext:
 ok:
 	run_truncate_around(run, vcn);
 out:
+	if (err && step > 1) {
+		/* Too complex to restore. */
+		_ntfs_bad_inode(&ni->vfs_inode);
+	}
 	up_write(&ni->file.run_lock);
 	ni_unlock(ni);
 
 	return err;
+
+undo1:
+	/* Undo step1. */
+	attr_b->nres.total_size = cpu_to_le64(total_size0);
+	inode_set_bytes(&ni->vfs_inode, total_size0);
+
+	if (run_deallocate_ex(sbi, run, vcn, alen, NULL, false) ||
+	    !run_add_entry(run, vcn, SPARSE_LCN, alen, false) ||
+	    mi_pack_runs(mi, attr, run, max(end, evcn1) - svcn)) {
+		_ntfs_bad_inode(&ni->vfs_inode);
+	}
+	goto out;
 }
 
 int attr_data_read_resident(struct ntfs_inode *ni, struct page *page)

fs/ntfs3/fsntfs.c

@@ -443,6 +443,39 @@ up_write:
 	return err;
 }
 
+/*
+ * ntfs_check_for_free_space
+ *
+ * Check if it is possible to allocate 'clen' clusters and 'mlen' Mft records
+ */
+bool ntfs_check_for_free_space(struct ntfs_sb_info *sbi, CLST clen, CLST mlen)
+{
+	size_t free, zlen, avail;
+	struct wnd_bitmap *wnd;
+
+	wnd = &sbi->used.bitmap;
+	down_read_nested(&wnd->rw_lock, BITMAP_MUTEX_CLUSTERS);
+	free = wnd_zeroes(wnd);
+	zlen = wnd_zone_len(wnd);
+	up_read(&wnd->rw_lock);
+
+	if (free < zlen + clen)
+		return false;
+
+	avail = free - (zlen + clen);
+
+	wnd = &sbi->mft.bitmap;
+	down_read_nested(&wnd->rw_lock, BITMAP_MUTEX_MFT);
+	free = wnd_zeroes(wnd);
+	zlen = wnd_zone_len(wnd);
+	up_read(&wnd->rw_lock);
+
+	if (free >= zlen + mlen)
+		return true;
+
+	return avail >= bytes_to_cluster(sbi, mlen << sbi->record_bits);
+}
+
 /*
  * ntfs_extend_mft - Allocate additional MFT records.
  *

fs/ntfs3/ntfs_fs.h

@@ -588,6 +588,7 @@ int ntfs_loadlog_and_replay(struct ntfs_inode *ni, struct ntfs_sb_info *sbi);
 int ntfs_look_for_free_space(struct ntfs_sb_info *sbi, CLST lcn, CLST len,
 			     CLST *new_lcn, CLST *new_len,
 			     enum ALLOCATE_OPT opt);
+bool ntfs_check_for_free_space(struct ntfs_sb_info *sbi, CLST clen, CLST mlen);
 int ntfs_look_free_mft(struct ntfs_sb_info *sbi, CLST *rno, bool mft,
 		       struct ntfs_inode *ni, struct mft_inode **mi);
 void ntfs_mark_rec_free(struct ntfs_sb_info *sbi, CLST rno, bool is_mft);