From: Chunwei Chen <tuxoko@gmail.com>
Date: Mon, 19 Aug 2024 16:42:17 +0000 (-0700)
Subject: Skip ro check for snaps when multi-mount
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=06a7b123acaaedc36926ab45b3cf61396702dc1d;p=mirror_zfs.git

Skip ro check for snaps when multi-mount

Skip ro check for snapshots since they are always ro regardless if ro
flag is passed by mount or not. This allows multi-mounting snapshots
without requiring to specify ro flag.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@nutanix.com>
Closes #16299
---

diff --git a/module/os/linux/zfs/zpl_super.c b/module/os/linux/zfs/zpl_super.c
index d98d32c1f..0a82b8858 100644
--- a/module/os/linux/zfs/zpl_super.c
+++ b/module/os/linux/zfs/zpl_super.c
@@ -292,6 +292,7 @@ zpl_mount_impl(struct file_system_type *fs_type, int flags, zfs_mnt_t *zm)
 {
 	struct super_block *s;
 	objset_t *os;
+	boolean_t issnap = B_FALSE;
 	int err;
 
 	err = dmu_objset_hold(zm->mnt_osname, FTAG, &os);
@@ -323,6 +324,7 @@ zpl_mount_impl(struct file_system_type *fs_type, int flags, zfs_mnt_t *zm)
 		if (zpl_enter(zfsvfs, FTAG) == 0) {
 			if (os != zfsvfs->z_os)
 				err = -SET_ERROR(EBUSY);
+			issnap = zfsvfs->z_issnap;
 			zpl_exit(zfsvfs, FTAG);
 		} else {
 			err = -SET_ERROR(EBUSY);
@@ -346,7 +348,11 @@ zpl_mount_impl(struct file_system_type *fs_type, int flags, zfs_mnt_t *zm)
 			return (ERR_PTR(err));
 		}
 		s->s_flags |= SB_ACTIVE;
-	} else if ((flags ^ s->s_flags) & SB_RDONLY) {
+	} else if (!issnap && ((flags ^ s->s_flags) & SB_RDONLY)) {
+		/*
+		 * Skip ro check for snap since snap is always ro regardless
+		 * ro flag is passed by mount or not.
+		 */
 		deactivate_locked_super(s);
 		return (ERR_PTR(-EBUSY));
 	}