From 7966cbba53890e1010861b75bd9923e793bbc975 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 18 Apr 2018 13:31:38 +1000 Subject: [PATCH] libmount: fix mnt_table_is_fs_mounted() for NFS bind mounts. When you bind-mount a subdirectory of a local filesystem, the path to that subdirectory appears as the fourth field in mountinfo. For nfs mounts, the fourth field is always "/", and the subdirectory part is appended to the "special" (aka "device") field. This is consistent with historical NFS usage which always includes a path in the fs_spec field. libmount needs to know about this when "mount -a" checks to see if a filesystem is already mounted. Without this fix, fstab lines like: server::/path /dir nfs defaults 0 0 /dir/subdir /mnt/test none bind 0 0 result in a new mount at /mnt/test every time "mount -a" is run. [kzak@redhat.com: - use strappend() rather than asprintf()] Signed-off-by: NeilBrown Signed-off-by: Karel Zak --- libmount/src/tab.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/libmount/src/tab.c b/libmount/src/tab.c index 968057e42..eb61dd33e 100644 --- a/libmount/src/tab.c +++ b/libmount/src/tab.c @@ -1542,6 +1542,7 @@ int mnt_table_is_fs_mounted(struct libmnt_table *tb, struct libmnt_fs *fstab_fs) struct libmnt_fs *fs; char *root = NULL; + char *src2 = NULL; const char *src = NULL, *tgt = NULL; char *xtgt = NULL; int rc = 0; @@ -1566,8 +1567,17 @@ int mnt_table_is_fs_mounted(struct libmnt_table *tb, struct libmnt_fs *fstab_fs) flags = MS_BIND; rootfs = mnt_table_get_fs_root(tb, fstab_fs, flags, &root); - if (rootfs) + if (rootfs) { + const char *fstype = mnt_fs_get_fstype(rootfs); + src = mnt_fs_get_srcpath(rootfs); + if (fstype && strncmp(fstype, "nfs", 3) == 0 && root) { + /* NFS stores the root at the end of the source */ + src = src2 = strappend(src, root); + free(root); + root = NULL; + } + } } if (!src) @@ -1667,6 +1677,7 @@ done: free(root); DBG(TAB, ul_debugobj(tb, "mnt_table_is_fs_mounted: %s [rc=%d]", src, rc)); + free(src2); return rc; } -- 2.16.3