A one-liner that leads to a startling (but also very much rational)

performance improvement in cases where an IMA policy with rules that
 are based on fsmagic matching is enforced, an encryption-related fixup
 that addresses generic/397 and other fstest failures and a couple of
 cleanups in CephFS.
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Merge tag 'ceph-for-6.16-rc1' of https://github.com/ceph/ceph-client

Pull ceph updates from Ilya Dryomov:

 - a one-liner that leads to a startling (but also very much rational)
   performance improvement in cases where an IMA policy with rules that
   are based on fsmagic matching is enforced

 - an encryption-related fixup that addresses generic/397 and other
   fstest failures

 - a couple of cleanups in CephFS

* tag 'ceph-for-6.16-rc1' of https://github.com/ceph/ceph-client:
  ceph: fix variable dereferenced before check in ceph_umount_begin()
  ceph: set superblock s_magic for IMA fsmagic matching
  ceph: cleanup hardcoded constants of file handle size
  ceph: fix possible integer overflow in ceph_zero_objects()
  ceph: avoid kernel BUG for encrypted inode with unaligned file size

fs/ceph/addr.c

@@ -409,6 +409,15 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
 		struct page **pages;
 		size_t page_off;
 
+		/*
+		 * FIXME: io_iter.count needs to be corrected to aligned
+		 * length. Otherwise, iov_iter_get_pages_alloc2() operates
+		 * with the initial unaligned length value. As a result,
+		 * ceph_msg_data_cursor_init() triggers BUG_ON() in the case
+		 * if msg->sparse_read_total > msg->data_length.
+		 */
+		subreq->io_iter.count = len;
+
 		err = iov_iter_get_pages_alloc2(&subreq->io_iter, &pages, len, &page_off);
 		if (err < 0) {
 			doutc(cl, "%llx.%llx failed to allocate pages, %d\n",

fs/ceph/export.c

@@ -33,12 +33,19 @@ struct ceph_nfs_snapfh {
 	u32 hash;
 } __attribute__ ((packed));
 
+#define BYTES_PER_U32		(sizeof(u32))
+#define CEPH_FH_BASIC_SIZE \
+	(sizeof(struct ceph_nfs_fh) / BYTES_PER_U32)
+#define CEPH_FH_WITH_PARENT_SIZE \
+	(sizeof(struct ceph_nfs_confh) / BYTES_PER_U32)
+#define CEPH_FH_SNAPPED_INODE_SIZE \
+	(sizeof(struct ceph_nfs_snapfh) / BYTES_PER_U32)
+
 static int ceph_encode_snapfh(struct inode *inode, u32 *rawfh, int *max_len,
 			      struct inode *parent_inode)
 {
 	struct ceph_client *cl = ceph_inode_to_client(inode);
-	static const int snap_handle_length =
+	static const int snap_handle_length = CEPH_FH_SNAPPED_INODE_SIZE;
-		sizeof(struct ceph_nfs_snapfh) >> 2;
 	struct ceph_nfs_snapfh *sfh = (void *)rawfh;
 	u64 snapid = ceph_snap(inode);
 	int ret;
@@ -88,10 +95,8 @@ static int ceph_encode_fh(struct inode *inode, u32 *rawfh, int *max_len,
 			  struct inode *parent_inode)
 {
 	struct ceph_client *cl = ceph_inode_to_client(inode);
-	static const int handle_length =
+	static const int handle_length = CEPH_FH_BASIC_SIZE;
-		sizeof(struct ceph_nfs_fh) >> 2;
+	static const int connected_handle_length = CEPH_FH_WITH_PARENT_SIZE;
-	static const int connected_handle_length =
-		sizeof(struct ceph_nfs_confh) >> 2;
 	int type;
 
 	if (ceph_snap(inode) != CEPH_NOSNAP)
@@ -308,7 +313,7 @@ static struct dentry *ceph_fh_to_dentry(struct super_block *sb,
 	if (fh_type != FILEID_INO32_GEN  &&
 	    fh_type != FILEID_INO32_GEN_PARENT)
 		return NULL;
-	if (fh_len < sizeof(*fh) / 4)
+	if (fh_len < sizeof(*fh) / BYTES_PER_U32)
 		return NULL;
 
 	doutc(fsc->client, "%llx\n", fh->ino);
@@ -427,7 +432,7 @@ static struct dentry *ceph_fh_to_parent(struct super_block *sb,
 
 	if (fh_type != FILEID_INO32_GEN_PARENT)
 		return NULL;
-	if (fh_len < sizeof(*cfh) / 4)
+	if (fh_len < sizeof(*cfh) / BYTES_PER_U32)
 		return NULL;
 
 	doutc(fsc->client, "%llx\n", cfh->parent_ino);

fs/ceph/file.c

@@ -2616,7 +2616,7 @@ static int ceph_zero_objects(struct inode *inode, loff_t offset, loff_t length)
 	s32 stripe_unit = ci->i_layout.stripe_unit;
 	s32 stripe_count = ci->i_layout.stripe_count;
 	s32 object_size = ci->i_layout.object_size;
-	u64 object_set_size = object_size * stripe_count;
+	u64 object_set_size = (u64) object_size * stripe_count;
 	u64 nearly, t;
 
 	/* round offset up to next period boundary */

fs/ceph/super.c

@@ -1033,8 +1033,7 @@ void ceph_umount_begin(struct super_block *sb)
 	struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);
 
 	doutc(fsc->client, "starting forced umount\n");
-	if (!fsc)
+
-		return;
 	fsc->mount_state = CEPH_MOUNT_SHUTDOWN;
 	__ceph_umount_begin(fsc);
 }
@@ -1227,6 +1226,7 @@ static int ceph_set_super(struct super_block *s, struct fs_context *fc)
 	s->s_time_min = 0;
 	s->s_time_max = U32_MAX;
 	s->s_flags |= SB_NODIRATIME | SB_NOATIME;
+	s->s_magic = CEPH_SUPER_MAGIC;
 
 	ceph_fscrypt_set_ops(s);