[PATCH 0/3] Fix eject button handling for RO fs

[PATCH 0/3] Fix eject button handling for RO fs

[Jan Kara]

  Hello,

As Hui Wang reported, there is a problem with handling of eject button
for read-write media (i.e. CD-RW & DVD-RW). Although these are mounted
read-only, block layer thinks they are used read-write (unlike the case
when the media is normal CD or DVD disk) and thus blocks the eject
button.  This appears inconsistent to users and as Hui reports it is a
regression against pre-3.0 kernels.

Tejun suggested we can always use read-only access when filesystem is
going to be used read-only. With iso9660 this would work as it is always
read-only. But for udf this doesn't work as it can be used read-write.
Whether it is read-only or read-write depends on filesystem features so
we cannot tell before reading the disk.

The solution I've taken is that we return EACCES if we are asked to
mount a filesystem which can be mounted only read-only without MS_RDONLY
set (so far we just silently set the MS_RDONLY flag during mount). This
is userspace visible change which is why I'm CCing more people than
usual. But I'm convinced we should be fine for several reasons:
1) The behavior isn't new - when the media is read-only, userspace will
   already get EACCES when trying to mount it without MS_RDONLY set.
2) mount(8) retries with MS_RDONLY set when it gets EACCESS.
3) mount(2) manpage documents this behavior.

If noone will object to this change, I'll push the patches via my tree
to Linus.

								Honza

[PATCH 1/3] isofs: Refuse RW mount of the filesystem instead of making it RO

[Jan Kara]

Refuse RW mount of isofs filesystem. So far we just silently changed it
to RO mount but when the media is writeable, block layer won't notice
this change and thus will think device is used RW and will block eject
button of the drive. That is unexpected by users because for
non-writeable media eject button works just fine.

Userspace mount(8) command handles this just fine and retries mounting
with MS_RDONLY set so userspace shouldn't see any regression.  Plus any
tool mounting isofs is likely confronted with the case of read-only
media where block layer already refuses to mount the filesystem without
MS_RDONLY set so our behavior shouldn't be anything new for it.

Reported-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/isofs/inode.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c
index c348d6d..e5d408a 100644
--- a/fs/isofs/inode.c
+++ b/fs/isofs/inode.c
@@ -117,8 +117,8 @@ static void destroy_inodecache(void)
 
 static int isofs_remount(struct super_block *sb, int *flags, char *data)
 {
-	/* we probably want a lot more here */
-	*flags |= MS_RDONLY;
+	if (!(*flags & MS_RDONLY))
+		return -EROFS;
 	return 0;
 }
 
@@ -763,15 +763,6 @@ root_found:
 	 */
 	s->s_maxbytes = 0x80000000000LL;
 
-	/*
-	 * The CDROM is read-only, has no nodes (devices) on it, and since
-	 * all of the files appear to be owned by root, we really do not want
-	 * to allow suid.  (suid or devices will not show up unless we have
-	 * Rock Ridge extensions)
-	 */
-
-	s->s_flags |= MS_RDONLY /* | MS_NODEV | MS_NOSUID */;
-
 	/* Set this for reference. Its not currently used except on write
 	   which we don't have .. */
 
@@ -1530,6 +1521,9 @@ struct inode *isofs_iget(struct super_block *sb,
 static struct dentry *isofs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
+	/* We don't support read-write mounts */
+	if (!(flags & MS_RDONLY))
+		return ERR_PTR(-EACCES);
 	return mount_bdev(fs_type, flags, dev_name, data, isofs_fill_super);
 }
 
-- 
1.8.1.4

[PATCH 2/3] udf: Standardize return values in mount sequence

[Jan Kara]

Change all function used in filesystem discovery during mount to user
standard kernel return values - -errno on error, 0 on success instead
of 1 on failure and 0 on success. This allows us to pass error number
(not just failure / success) so we can abort device scanning earlier
in case of errors like EIO or ENOMEM . Also we will be able to return
EROFS in case writeable mount is requested but writing isn't supported.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/udf/super.c | 300 +++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 183 insertions(+), 117 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 9ac4057..c68da0d 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -843,27 +843,38 @@ static int udf_find_fileset(struct super_block *sb,
 	return 1;
 }
 
+/*
+ * Load primary Volume Descriptor Sequence
+ *
+ * Return <0 on error, 0 on success. -EAGAIN is special meaning next sequence
+ * should be tried.
+ */
 static int udf_load_pvoldesc(struct super_block *sb, sector_t block)
 {
 	struct primaryVolDesc *pvoldesc;
 	struct ustr *instr, *outstr;
 	struct buffer_head *bh;
 	uint16_t ident;
-	int ret = 1;
+	int ret = -ENOMEM;
 
 	instr = kmalloc(sizeof(struct ustr), GFP_NOFS);
 	if (!instr)
-		return 1;
+		return -ENOMEM;
 
 	outstr = kmalloc(sizeof(struct ustr), GFP_NOFS);
 	if (!outstr)
 		goto out1;
 
 	bh = udf_read_tagged(sb, block, block, &ident);
-	if (!bh)
+	if (!bh) {
+		ret = -EAGAIN;
 		goto out2;
+	}
 
-	BUG_ON(ident != TAG_IDENT_PVD);
+	if (ident != TAG_IDENT_PVD) {
+		ret = -EIO;
+		goto out_bh;
+	}
 
 	pvoldesc = (struct primaryVolDesc *)bh->b_data;
 
@@ -889,8 +900,9 @@ static int udf_load_pvoldesc(struct super_block *sb, sector_t block)
 		if (udf_CS0toUTF8(outstr, instr))
 			udf_debug("volSetIdent[] = '%s'\n", outstr->u_name);
 
-	brelse(bh);
 	ret = 0;
+out_bh:
+	brelse(bh);
 out2:
 	kfree(outstr);
 out1:
@@ -947,7 +959,7 @@ static int udf_load_metadata_files(struct super_block *sb, int partition)
 
 		if (mdata->s_mirror_fe == NULL) {
 			udf_err(sb, "Both metadata and mirror metadata inode efe can not found\n");
-			goto error_exit;
+			return -EIO;
 		}
 	}
 
@@ -964,23 +976,18 @@ static int udf_load_metadata_files(struct super_block *sb, int partition)
 			  addr.logicalBlockNum, addr.partitionReferenceNum);
 
 		mdata->s_bitmap_fe = udf_iget(sb, &addr);
-
 		if (mdata->s_bitmap_fe == NULL) {
 			if (sb->s_flags & MS_RDONLY)
 				udf_warn(sb, "bitmap inode efe not found but it's ok since the disc is mounted read-only\n");
 			else {
 				udf_err(sb, "bitmap inode efe not found and attempted read-write mount\n");
-				goto error_exit;
+				return -EIO;
 			}
 		}
 	}
 
 	udf_debug("udf_load_metadata_files Ok\n");
-
 	return 0;
-
-error_exit:
-	return 1;
 }
 
 static void udf_load_fileset(struct super_block *sb, struct buffer_head *bh,
@@ -1069,7 +1076,7 @@ static int udf_fill_partdesc_info(struct super_block *sb,
 		if (!map->s_uspace.s_table) {
 			udf_debug("cannot load unallocSpaceTable (part %d)\n",
 				  p_index);
-			return 1;
+			return -EIO;
 		}
 		map->s_partition_flags |= UDF_PART_FLAG_UNALLOC_TABLE;
 		udf_debug("unallocSpaceTable (part %d) @ %ld\n",
@@ -1079,7 +1086,7 @@ static int udf_fill_partdesc_info(struct super_block *sb,
 	if (phd->unallocSpaceBitmap.extLength) {
 		struct udf_bitmap *bitmap = udf_sb_alloc_bitmap(sb, p_index);
 		if (!bitmap)
-			return 1;
+			return -ENOMEM;
 		map->s_uspace.s_bitmap = bitmap;
 		bitmap->s_extPosition = le32_to_cpu(
 				phd->unallocSpaceBitmap.extPosition);
@@ -1102,7 +1109,7 @@ static int udf_fill_partdesc_info(struct super_block *sb,
 		if (!map->s_fspace.s_table) {
 			udf_debug("cannot load freedSpaceTable (part %d)\n",
 				  p_index);
-			return 1;
+			return -EIO;
 		}
 
 		map->s_partition_flags |= UDF_PART_FLAG_FREED_TABLE;
@@ -1113,7 +1120,7 @@ static int udf_fill_partdesc_info(struct super_block *sb,
 	if (phd->freedSpaceBitmap.extLength) {
 		struct udf_bitmap *bitmap = udf_sb_alloc_bitmap(sb, p_index);
 		if (!bitmap)
-			return 1;
+			return -ENOMEM;
 		map->s_fspace.s_bitmap = bitmap;
 		bitmap->s_extPosition = le32_to_cpu(
 				phd->freedSpaceBitmap.extPosition);
@@ -1165,7 +1172,7 @@ static int udf_load_vat(struct super_block *sb, int p_index, int type1_index)
 		udf_find_vat_block(sb, p_index, type1_index, blocks - 1);
 	}
 	if (!sbi->s_vat_inode)
-		return 1;
+		return -EIO;
 
 	if (map->s_partition_type == UDF_VIRTUAL_MAP15) {
 		map->s_type_specific.s_virtual.s_start_offset = 0;
@@ -1177,7 +1184,7 @@ static int udf_load_vat(struct super_block *sb, int p_index, int type1_index)
 			pos = udf_block_map(sbi->s_vat_inode, 0);
 			bh = sb_bread(sb, pos);
 			if (!bh)
-				return 1;
+				return -EIO;
 			vat20 = (struct virtualAllocationTable20 *)bh->b_data;
 		} else {
 			vat20 = (struct virtualAllocationTable20 *)
@@ -1195,6 +1202,12 @@ static int udf_load_vat(struct super_block *sb, int p_index, int type1_index)
 	return 0;
 }
 
+/*
+ * Load partition descriptor block
+ *
+ * Returns <0 on error, 0 on success, -EAGAIN is special - try next descriptor
+ * sequence.
+ */
 static int udf_load_partdesc(struct super_block *sb, sector_t block)
 {
 	struct buffer_head *bh;
@@ -1204,13 +1217,15 @@ static int udf_load_partdesc(struct super_block *sb, sector_t block)
 	int i, type1_idx;
 	uint16_t partitionNumber;
 	uint16_t ident;
-	int ret = 0;
+	int ret;
 
 	bh = udf_read_tagged(sb, block, block, &ident);
 	if (!bh)
-		return 1;
-	if (ident != TAG_IDENT_PD)
+		return -EAGAIN;
+	if (ident != TAG_IDENT_PD) {
+		ret = 0;
 		goto out_bh;
+	}
 
 	p = (struct partitionDesc *)bh->b_data;
 	partitionNumber = le16_to_cpu(p->partitionNumber);
@@ -1229,10 +1244,13 @@ static int udf_load_partdesc(struct super_block *sb, sector_t block)
 	if (i >= sbi->s_partitions) {
 		udf_debug("Partition (%d) not found in partition map\n",
 			  partitionNumber);
+		ret = 0;
 		goto out_bh;
 	}
 
 	ret = udf_fill_partdesc_info(sb, p, i);
+	if (ret < 0)
+		goto out_bh;
 
 	/*
 	 * Now rescan for VIRTUAL or METADATA partitions when SPARABLE and
@@ -1249,23 +1267,25 @@ static int udf_load_partdesc(struct super_block *sb, sector_t block)
 			break;
 	}
 
-	if (i >= sbi->s_partitions)
+	if (i >= sbi->s_partitions) {
+		ret = 0;
 		goto out_bh;
+	}
 
 	ret = udf_fill_partdesc_info(sb, p, i);
-	if (ret)
+	if (ret < 0)
 		goto out_bh;
 
 	if (map->s_partition_type == UDF_METADATA_MAP25) {
 		ret = udf_load_metadata_files(sb, i);
-		if (ret) {
+		if (ret < 0) {
 			udf_err(sb, "error loading MetaData partition map %d\n",
 				i);
 			goto out_bh;
 		}
 	} else {
 		ret = udf_load_vat(sb, i, type1_idx);
-		if (ret)
+		if (ret < 0)
 			goto out_bh;
 		/*
 		 * Mark filesystem read-only if we have a partition with
@@ -1275,6 +1295,7 @@ static int udf_load_partdesc(struct super_block *sb, sector_t block)
 		sb->s_flags |= MS_RDONLY;
 		pr_notice("Filesystem marked read-only because writing to pseudooverwrite partition is not implemented\n");
 	}
+	ret = 0;
 out_bh:
 	/* In case loading failed, we handle cleanup in udf_fill_super */
 	brelse(bh);
@@ -1340,11 +1361,11 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
 	uint16_t ident;
 	struct buffer_head *bh;
 	unsigned int table_len;
-	int ret = 0;
+	int ret;
 
 	bh = udf_read_tagged(sb, block, block, &ident);
 	if (!bh)
-		return 1;
+		return -EAGAIN;
 	BUG_ON(ident != TAG_IDENT_LVD);
 	lvd = (struct logicalVolDesc *)bh->b_data;
 	table_len = le32_to_cpu(lvd->mapTableLength);
@@ -1352,7 +1373,7 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
 		udf_err(sb, "error loading logical volume descriptor: "
 			"Partition table too long (%u > %lu)\n", table_len,
 			sb->s_blocksize - sizeof(*lvd));
-		ret = 1;
+		ret = -EIO;
 		goto out_bh;
 	}
 
@@ -1396,11 +1417,10 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
 			} else if (!strncmp(upm2->partIdent.ident,
 						UDF_ID_SPARABLE,
 						strlen(UDF_ID_SPARABLE))) {
-				if (udf_load_sparable_map(sb, map,
-				    (struct sparablePartitionMap *)gpm) < 0) {
-					ret = 1;
+				ret = udf_load_sparable_map(sb, map,
+					(struct sparablePartitionMap *)gpm);
+				if (ret < 0)
 					goto out_bh;
-				}
 			} else if (!strncmp(upm2->partIdent.ident,
 						UDF_ID_METADATA,
 						strlen(UDF_ID_METADATA))) {
@@ -1465,7 +1485,7 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
 	}
 	if (lvd->integritySeqExt.extLength)
 		udf_load_logicalvolint(sb, leea_to_cpu(lvd->integritySeqExt));
-
+	ret = 0;
 out_bh:
 	brelse(bh);
 	return ret;
@@ -1503,22 +1523,18 @@ static void udf_load_logicalvolint(struct super_block *sb, struct kernel_extent_
 }
 
 /*
- * udf_process_sequence
- *
- * PURPOSE
- *	Process a main/reserve volume descriptor sequence.
+ * Process a main/reserve volume descriptor sequence.
+ *   @block		First block of first extent of the sequence.
+ *   @lastblock		Lastblock of first extent of the sequence.
+ *   @fileset		There we store extent containing root fileset
  *
- * PRE-CONDITIONS
- *	sb			Pointer to _locked_ superblock.
- *	block			First block of first extent of the sequence.
- *	lastblock		Lastblock of first extent of the sequence.
- *
- * HISTORY
- *	July 1, 1997 - Andrew E. Mileski
- *	Written, tested, and released.
+ * Returns <0 on error, 0 on success. -EAGAIN is special - try next descriptor
+ * sequence
  */
-static noinline int udf_process_sequence(struct super_block *sb, long block,
-				long lastblock, struct kernel_lb_addr *fileset)
+static noinline int udf_process_sequence(
+		struct super_block *sb,
+		sector_t block, sector_t lastblock,
+		struct kernel_lb_addr *fileset)
 {
 	struct buffer_head *bh = NULL;
 	struct udf_vds_record vds[VDS_POS_LENGTH];
@@ -1529,6 +1545,7 @@ static noinline int udf_process_sequence(struct super_block *sb, long block,
 	uint32_t vdsn;
 	uint16_t ident;
 	long next_s = 0, next_e = 0;
+	int ret;
 
 	memset(vds, 0, sizeof(struct udf_vds_record) * VDS_POS_LENGTH);
 
@@ -1543,7 +1560,7 @@ static noinline int udf_process_sequence(struct super_block *sb, long block,
 			udf_err(sb,
 				"Block %llu of volume descriptor sequence is corrupted or we could not read it\n",
 				(unsigned long long)block);
-			return 1;
+			return -EAGAIN;
 		}
 
 		/* Process each descriptor (ISO 13346 3/8.3-8.4) */
@@ -1616,14 +1633,19 @@ static noinline int udf_process_sequence(struct super_block *sb, long block,
 	 */
 	if (!vds[VDS_POS_PRIMARY_VOL_DESC].block) {
 		udf_err(sb, "Primary Volume Descriptor not found!\n");
-		return 1;
+		return -EAGAIN;
+	}
+	ret = udf_load_pvoldesc(sb, vds[VDS_POS_PRIMARY_VOL_DESC].block);
+	if (ret < 0)
+		return ret;
+
+	if (vds[VDS_POS_LOGICAL_VOL_DESC].block) {
+		ret = udf_load_logicalvol(sb,
+					  vds[VDS_POS_LOGICAL_VOL_DESC].block,
+					  fileset);
+		if (ret < 0)
+			return ret;
 	}
-	if (udf_load_pvoldesc(sb, vds[VDS_POS_PRIMARY_VOL_DESC].block))
-		return 1;
-
-	if (vds[VDS_POS_LOGICAL_VOL_DESC].block && udf_load_logicalvol(sb,
-	    vds[VDS_POS_LOGICAL_VOL_DESC].block, fileset))
-		return 1;
 
 	if (vds[VDS_POS_PARTITION_DESC].block) {
 		/*
@@ -1632,19 +1654,27 @@ static noinline int udf_process_sequence(struct super_block *sb, long block,
 		 */
 		for (block = vds[VDS_POS_PARTITION_DESC].block;
 		     block < vds[VDS_POS_TERMINATING_DESC].block;
-		     block++)
-			if (udf_load_partdesc(sb, block))
-				return 1;
+		     block++) {
+			ret = udf_load_partdesc(sb, block);
+			if (ret < 0)
+				return ret;
+		}
 	}
 
 	return 0;
 }
 
+/*
+ * Load Volume Descriptor Sequence described by anchor in bh
+ *
+ * Returns <0 on error, 0 on success
+ */
 static int udf_load_sequence(struct super_block *sb, struct buffer_head *bh,
 			     struct kernel_lb_addr *fileset)
 {
 	struct anchorVolDescPtr *anchor;
-	long main_s, main_e, reserve_s, reserve_e;
+	sector_t main_s, main_e, reserve_s, reserve_e;
+	int ret;
 
 	anchor = (struct anchorVolDescPtr *)bh->b_data;
 
@@ -1662,18 +1692,26 @@ static int udf_load_sequence(struct super_block *sb, struct buffer_head *bh,
 
 	/* Process the main & reserve sequences */
 	/* responsible for finding the PartitionDesc(s) */
-	if (!udf_process_sequence(sb, main_s, main_e, fileset))
-		return 1;
-	udf_sb_free_partitions(sb);
-	if (!udf_process_sequence(sb, reserve_s, reserve_e, fileset))
-		return 1;
+	ret = udf_process_sequence(sb, main_s, main_e, fileset);
+	if (ret != -EAGAIN)
+		return ret;
 	udf_sb_free_partitions(sb);
-	return 0;
+	ret = udf_process_sequence(sb, reserve_s, reserve_e, fileset);
+	if (ret < 0) {
+		udf_sb_free_partitions(sb);
+		/* No sequence was OK, return -EIO */
+		if (ret == -EAGAIN)
+			ret = -EIO;
+	}
+	return ret;
 }
 
 /*
  * Check whether there is an anchor block in the given block and
  * load Volume Descriptor Sequence if so.
+ *
+ * Returns <0 on error, 0 on success, -EAGAIN is special - try next anchor
+ * block
  */
 static int udf_check_anchor_block(struct super_block *sb, sector_t block,
 				  struct kernel_lb_addr *fileset)
@@ -1685,33 +1723,40 @@ static int udf_check_anchor_block(struct super_block *sb, sector_t block,
 	if (UDF_QUERY_FLAG(sb, UDF_FLAG_VARCONV) &&
 	    udf_fixed_to_variable(block) >=
 	    sb->s_bdev->bd_inode->i_size >> sb->s_blocksize_bits)
-		return 0;
+		return -EAGAIN;
 
 	bh = udf_read_tagged(sb, block, block, &ident);
 	if (!bh)
-		return 0;
+		return -EAGAIN;
 	if (ident != TAG_IDENT_AVDP) {
 		brelse(bh);
-		return 0;
+		return -EAGAIN;
 	}
 	ret = udf_load_sequence(sb, bh, fileset);
 	brelse(bh);
 	return ret;
 }
 
-/* Search for an anchor volume descriptor pointer */
-static sector_t udf_scan_anchors(struct super_block *sb, sector_t lastblock,
-				 struct kernel_lb_addr *fileset)
+/*
+ * Search for an anchor volume descriptor pointer.
+ *
+ * Returns < 0 on error, 0 on success. -EAGAIN is special - try next set
+ * of anchors.
+ */
+static int udf_scan_anchors(struct super_block *sb, sector_t *lastblock,
+			    struct kernel_lb_addr *fileset)
 {
 	sector_t last[6];
 	int i;
 	struct udf_sb_info *sbi = UDF_SB(sb);
 	int last_count = 0;
+	int ret;
 
 	/* First try user provided anchor */
 	if (sbi->s_anchor) {
-		if (udf_check_anchor_block(sb, sbi->s_anchor, fileset))
-			return lastblock;
+		ret = udf_check_anchor_block(sb, sbi->s_anchor, fileset);
+		if (ret != -EAGAIN)
+			return ret;
 	}
 	/*
 	 * according to spec, anchor is in either:
@@ -1720,39 +1765,46 @@ static sector_t udf_scan_anchors(struct super_block *sb, sector_t lastblock,
 	 *     lastblock
 	 *  however, if the disc isn't closed, it could be 512.
 	 */
-	if (udf_check_anchor_block(sb, sbi->s_session + 256, fileset))
-		return lastblock;
+	ret = udf_check_anchor_block(sb, sbi->s_session + 256, fileset);
+	if (ret != -EAGAIN)
+		return ret;
 	/*
 	 * The trouble is which block is the last one. Drives often misreport
 	 * this so we try various possibilities.
 	 */
-	last[last_count++] = lastblock;
-	if (lastblock >= 1)
-		last[last_count++] = lastblock - 1;
-	last[last_count++] = lastblock + 1;
-	if (lastblock >= 2)
-		last[last_count++] = lastblock - 2;
-	if (lastblock >= 150)
-		last[last_count++] = lastblock - 150;
-	if (lastblock >= 152)
-		last[last_count++] = lastblock - 152;
+	last[last_count++] = *lastblock;
+	if (*lastblock >= 1)
+		last[last_count++] = *lastblock - 1;
+	last[last_count++] = *lastblock + 1;
+	if (*lastblock >= 2)
+		last[last_count++] = *lastblock - 2;
+	if (*lastblock >= 150)
+		last[last_count++] = *lastblock - 150;
+	if (*lastblock >= 152)
+		last[last_count++] = *lastblock - 152;
 
 	for (i = 0; i < last_count; i++) {
 		if (last[i] >= sb->s_bdev->bd_inode->i_size >>
 				sb->s_blocksize_bits)
 			continue;
-		if (udf_check_anchor_block(sb, last[i], fileset))
-			return last[i];
+		ret = udf_check_anchor_block(sb, last[i], fileset);
+		if (ret != -EAGAIN) {
+			if (!ret)
+				*lastblock = last[i];
+			return ret;
+		}
 		if (last[i] < 256)
 			continue;
-		if (udf_check_anchor_block(sb, last[i] - 256, fileset))
-			return last[i];
+		ret = udf_check_anchor_block(sb, last[i] - 256, fileset);
+		if (ret != -EAGAIN) {
+			if (!ret)
+				*lastblock = last[i];
+			return ret;
+		}
 	}
 
 	/* Finally try block 512 in case media is open */
-	if (udf_check_anchor_block(sb, sbi->s_session + 512, fileset))
-		return last[0];
-	return 0;
+	return udf_check_anchor_block(sb, sbi->s_session + 512, fileset);
 }
 
 /*
@@ -1760,54 +1812,59 @@ static sector_t udf_scan_anchors(struct super_block *sb, sector_t lastblock,
  * area specified by it. The function expects sbi->s_lastblock to be the last
  * block on the media.
  *
- * Return 1 if ok, 0 if not found.
- *
+ * Return <0 on error, 0 if anchor found. -EAGAIN is special meaning anchor
+ * was not found.
  */
 static int udf_find_anchor(struct super_block *sb,
 			   struct kernel_lb_addr *fileset)
 {
-	sector_t lastblock;
 	struct udf_sb_info *sbi = UDF_SB(sb);
+	sector_t lastblock = sbi->s_last_block;
+	int ret;
 
-	lastblock = udf_scan_anchors(sb, sbi->s_last_block, fileset);
-	if (lastblock)
+	ret = udf_scan_anchors(sb, &lastblock, fileset);
+	if (ret != -EAGAIN)
 		goto out;
 
 	/* No anchor found? Try VARCONV conversion of block numbers */
 	UDF_SET_FLAG(sb, UDF_FLAG_VARCONV);
+	lastblock = udf_variable_to_fixed(sbi->s_last_block);
 	/* Firstly, we try to not convert number of the last block */
-	lastblock = udf_scan_anchors(sb,
-				udf_variable_to_fixed(sbi->s_last_block),
-				fileset);
-	if (lastblock)
+	ret = udf_scan_anchors(sb, &lastblock, fileset);
+	if (ret != -EAGAIN)
 		goto out;
 
+	lastblock = sbi->s_last_block;
 	/* Secondly, we try with converted number of the last block */
-	lastblock = udf_scan_anchors(sb, sbi->s_last_block, fileset);
-	if (!lastblock) {
+	ret = udf_scan_anchors(sb, &lastblock, fileset);
+	if (ret < 0) {
 		/* VARCONV didn't help. Clear it. */
 		UDF_CLEAR_FLAG(sb, UDF_FLAG_VARCONV);
-		return 0;
 	}
 out:
-	sbi->s_last_block = lastblock;
-	return 1;
+	if (ret == 0)
+		sbi->s_last_block = lastblock;
+	return ret;
 }
 
 /*
  * Check Volume Structure Descriptor, find Anchor block and load Volume
- * Descriptor Sequence
+ * Descriptor Sequence.
+ *
+ * Returns < 0 on error, 0 on success. -EAGAIN is special meaning anchor
+ * block was not found.
  */
 static int udf_load_vrs(struct super_block *sb, struct udf_options *uopt,
 			int silent, struct kernel_lb_addr *fileset)
 {
 	struct udf_sb_info *sbi = UDF_SB(sb);
 	loff_t nsr_off;
+	int ret;
 
 	if (!sb_set_blocksize(sb, uopt->blocksize)) {
 		if (!silent)
 			udf_warn(sb, "Bad block size\n");
-		return 0;
+		return -EINVAL;
 	}
 	sbi->s_last_block = uopt->lastblock;
 	if (!uopt->novrs) {
@@ -1828,12 +1885,13 @@ static int udf_load_vrs(struct super_block *sb, struct udf_options *uopt,
 
 	/* Look for anchor block and load Volume Descriptor Sequence */
 	sbi->s_anchor = uopt->anchor;
-	if (!udf_find_anchor(sb, fileset)) {
-		if (!silent)
+	ret = udf_find_anchor(sb, fileset);
+	if (ret < 0) {
+		if (!silent && ret == -EAGAIN)
 			udf_warn(sb, "No anchor found\n");
-		return 0;
+		return ret;
 	}
-	return 1;
+	return 0;
 }
 
 static void udf_open_lvid(struct super_block *sb)
@@ -1939,7 +1997,7 @@ u64 lvid_get_unique_id(struct super_block *sb)
 
 static int udf_fill_super(struct super_block *sb, void *options, int silent)
 {
-	int ret;
+	int ret = -EINVAL;
 	struct inode *inode = NULL;
 	struct udf_options uopt;
 	struct kernel_lb_addr rootdir, fileset;
@@ -2011,7 +2069,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 	} else {
 		uopt.blocksize = bdev_logical_block_size(sb->s_bdev);
 		ret = udf_load_vrs(sb, &uopt, silent, &fileset);
-		if (!ret && uopt.blocksize != UDF_DEFAULT_BLOCKSIZE) {
+		if (ret == -EAGAIN && uopt.blocksize != UDF_DEFAULT_BLOCKSIZE) {
 			if (!silent)
 				pr_notice("Rescanning with blocksize %d\n",
 					  UDF_DEFAULT_BLOCKSIZE);
@@ -2021,8 +2079,11 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 			ret = udf_load_vrs(sb, &uopt, silent, &fileset);
 		}
 	}
-	if (!ret) {
-		udf_warn(sb, "No partition found (1)\n");
+	if (ret < 0) {
+		if (ret == -EAGAIN) {
+			udf_warn(sb, "No partition found (1)\n");
+			ret = -EINVAL;
+		}
 		goto error_out;
 	}
 
@@ -2040,6 +2101,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 			udf_err(sb, "minUDFReadRev=%x (max is %x)\n",
 				le16_to_cpu(lvidiu->minUDFReadRev),
 				UDF_MAX_READ_VERSION);
+			ret = -EINVAL;
 			goto error_out;
 		} else if (minUDFWriteRev > UDF_MAX_WRITE_VERSION)
 			sb->s_flags |= MS_RDONLY;
@@ -2054,6 +2116,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 
 	if (!sbi->s_partitions) {
 		udf_warn(sb, "No partition found (2)\n");
+		ret = -EINVAL;
 		goto error_out;
 	}
 
@@ -2065,6 +2128,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 
 	if (udf_find_fileset(sb, &fileset, &rootdir)) {
 		udf_warn(sb, "No fileset found\n");
+		ret = -EINVAL;
 		goto error_out;
 	}
 
@@ -2086,6 +2150,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 	if (!inode) {
 		udf_err(sb, "Error in udf_iget, block=%d, partition=%d\n",
 		       rootdir.logicalBlockNum, rootdir.partitionReferenceNum);
+		ret = -EIO;
 		goto error_out;
 	}
 
@@ -2093,6 +2158,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 	sb->s_root = d_make_root(inode);
 	if (!sb->s_root) {
 		udf_err(sb, "Couldn't allocate root dentry\n");
+		ret = -ENOMEM;
 		goto error_out;
 	}
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
@@ -2113,7 +2179,7 @@ error_out:
 	kfree(sbi);
 	sb->s_fs_info = NULL;
 
-	return -EINVAL;
+	return ret;
 }
 
 void _udf_err(struct super_block *sb, const char *function,
-- 
1.8.1.4

[PATCH 3/3] udf: Refuse RW mount of the filesystem instead of making it RO

[Jan Kara]

Refuse RW mount of udf filesystem. So far we just silently changed it
to RO mount but when the media is writeable, block layer won't notice
this change and thus will think device is used RW and will block eject
button of the drive. That is unexpected by users because for
non-writeable media eject button works just fine.

Userspace mount(8) command handles this just fine and retries mounting
with MS_RDONLY set so userspace shouldn't see any regression.  Plus any
tool mounting udf is likely confronted with the case of read-only
media where block layer already refuses to mount the filesystem without
MS_RDONLY set so our behavior shouldn't be anything new for it.

Reported-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/udf/super.c | 42 ++++++++++++++++++++++++------------------
 1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index c68da0d..839a2ba 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -630,6 +630,12 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
 	struct udf_sb_info *sbi = UDF_SB(sb);
 	int error = 0;
 
+	if (sbi->s_lvid_bh) {
+		int write_rev = le16_to_cpu(udf_sb_lvidiu(sbi)->minUDFWriteRev);
+		if (write_rev > UDF_MAX_WRITE_VERSION && !(*flags & MS_RDONLY))
+			return -EACCES;
+	}
+
 	uopt.flags = sbi->s_flags;
 	uopt.uid   = sbi->s_uid;
 	uopt.gid   = sbi->s_gid;
@@ -649,12 +655,6 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
 	sbi->s_dmode = uopt.dmode;
 	write_unlock(&sbi->s_cred_lock);
 
-	if (sbi->s_lvid_bh) {
-		int write_rev = le16_to_cpu(udf_sb_lvidiu(sbi)->minUDFWriteRev);
-		if (write_rev > UDF_MAX_WRITE_VERSION)
-			*flags |= MS_RDONLY;
-	}
-
 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 		goto out_unlock;
 
@@ -1284,16 +1284,18 @@ static int udf_load_partdesc(struct super_block *sb, sector_t block)
 			goto out_bh;
 		}
 	} else {
+		/*
+		 * If we have a partition with virtual map, we don't handle
+		 * writing to it (we overwrite blocks instead of relocating
+		 * them).
+		 */
+		if (!(sb->s_flags & MS_RDONLY)) {
+			ret = -EACCES;
+			goto out_bh;
+		}
 		ret = udf_load_vat(sb, i, type1_idx);
 		if (ret < 0)
 			goto out_bh;
-		/*
-		 * Mark filesystem read-only if we have a partition with
-		 * virtual map since we don't handle writing to it (we
-		 * overwrite blocks instead of relocating them).
-		 */
-		sb->s_flags |= MS_RDONLY;
-		pr_notice("Filesystem marked read-only because writing to pseudooverwrite partition is not implemented\n");
 	}
 	ret = 0;
 out_bh:
@@ -2103,8 +2105,11 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 				UDF_MAX_READ_VERSION);
 			ret = -EINVAL;
 			goto error_out;
-		} else if (minUDFWriteRev > UDF_MAX_WRITE_VERSION)
-			sb->s_flags |= MS_RDONLY;
+		} else if (minUDFWriteRev > UDF_MAX_WRITE_VERSION &&
+			   !(sb->s_flags & MS_RDONLY)) {
+			ret = -EACCES;
+			goto error_out;
+		}
 
 		sbi->s_udfrev = minUDFWriteRev;
 
@@ -2121,9 +2126,10 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 	}
 
 	if (sbi->s_partmaps[sbi->s_partition].s_partition_flags &
-			UDF_PART_FLAG_READ_ONLY) {
-		pr_notice("Partition marked readonly; forcing readonly mount\n");
-		sb->s_flags |= MS_RDONLY;
+			UDF_PART_FLAG_READ_ONLY &&
+	    !(sb->s_flags & MS_RDONLY)) {
+		ret = -EACCES;
+		goto error_out;
 	}
 
 	if (udf_find_fileset(sb, &fileset, &rootdir)) {
-- 
1.8.1.4

Re: [PATCH 1/3] isofs: Refuse RW mount of the filesystem instead of making it RO

[Jan Kara]

On Fri 26-07-13 00:28:11, Jan Kara wrote:
> Refuse RW mount of isofs filesystem. So far we just silently changed it
> to RO mount but when the media is writeable, block layer won't notice
> this change and thus will think device is used RW and will block eject
> button of the drive. That is unexpected by users because for
> non-writeable media eject button works just fine.
> 
> Userspace mount(8) command handles this just fine and retries mounting
> with MS_RDONLY set so userspace shouldn't see any regression.  Plus any
> tool mounting isofs is likely confronted with the case of read-only
> media where block layer already refuses to mount the filesystem without
> MS_RDONLY set so our behavior shouldn't be anything new for it.
  OK, since noone objected to this patch series, I've merged the patches to
for_next branch in my tree.

								Honza

> 
> Reported-by: Hui Wang <hui.wang@canonical.com>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/isofs/inode.c | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c
> index c348d6d..e5d408a 100644
> --- a/fs/isofs/inode.c
> +++ b/fs/isofs/inode.c
> @@ -117,8 +117,8 @@ static void destroy_inodecache(void)
>  
>  static int isofs_remount(struct super_block *sb, int *flags, char *data)
>  {
> -	/* we probably want a lot more here */
> -	*flags |= MS_RDONLY;
> +	if (!(*flags & MS_RDONLY))
> +		return -EROFS;
>  	return 0;
>  }
>  
> @@ -763,15 +763,6 @@ root_found:
>  	 */
>  	s->s_maxbytes = 0x80000000000LL;
>  
> -	/*
> -	 * The CDROM is read-only, has no nodes (devices) on it, and since
> -	 * all of the files appear to be owned by root, we really do not want
> -	 * to allow suid.  (suid or devices will not show up unless we have
> -	 * Rock Ridge extensions)
> -	 */
> -
> -	s->s_flags |= MS_RDONLY /* | MS_NODEV | MS_NOSUID */;
> -
>  	/* Set this for reference. Its not currently used except on write
>  	   which we don't have .. */
>  
> @@ -1530,6 +1521,9 @@ struct inode *isofs_iget(struct super_block *sb,
>  static struct dentry *isofs_mount(struct file_system_type *fs_type,
>  	int flags, const char *dev_name, void *data)
>  {
> +	/* We don't support read-write mounts */
> +	if (!(flags & MS_RDONLY))
> +		return ERR_PTR(-EACCES);
>  	return mount_bdev(fs_type, flags, dev_name, data, isofs_fill_super);
>  }
>  
> -- 
> 1.8.1.4
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR