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authorMiklos Szeredi <mszeredi@redhat.com>2020-05-14 16:44:24 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2020-05-14 16:44:24 +0200
commit80340fe3605c0e78cfe496c3b3878be828cfdbfe (patch)
treea579a0172a6e31a9fe0b11c186f130a4fe9479a6
parentfa2fcf4f1df1559a0a4ee0f46915b496cc2ebf60 (diff)
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statx: add mount_root
Determining whether a path or file descriptor refers to a mountpoint (or more precisely a mount root) is not trivial using current tools. Add a flag to statx that indicates whether the path or fd refers to the root of a mount or not. Cc: linux-api@vger.kernel.org Cc: linux-man@vger.kernel.org Reported-by: Lennart Poettering <mzxreary@0pointer.de> Reported-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
-rw-r--r--fs/stat.c3
-rw-r--r--include/uapi/linux/stat.h1
2 files changed, 4 insertions, 0 deletions
diff --git a/fs/stat.c b/fs/stat.c
index 3d88c99f7743..b9faa6cafafe 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -202,6 +202,9 @@ retry:
error = vfs_getattr(&path, stat, request_mask, flags);
stat->mnt_id = real_mount(path.mnt)->mnt_id;
stat->result_mask |= STATX_MNT_ID;
+ if (path.mnt->mnt_root == path.dentry)
+ stat->attributes |= STATX_ATTR_MOUNT_ROOT;
+ stat->attributes_mask |= STATX_ATTR_MOUNT_ROOT;
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
index d81456247f10..6df9348bb277 100644
--- a/include/uapi/linux/stat.h
+++ b/include/uapi/linux/stat.h
@@ -181,6 +181,7 @@ struct statx {
#define STATX_ATTR_NODUMP 0x00000040 /* [I] File is not to be dumped */
#define STATX_ATTR_ENCRYPTED 0x00000800 /* [I] File requires key to decrypt in fs */
#define STATX_ATTR_AUTOMOUNT 0x00001000 /* Dir: Automount trigger */
+#define STATX_ATTR_MOUNT_ROOT 0x00002000 /* Root of a mount */
#define STATX_ATTR_VERITY 0x00100000 /* [I] Verity protected file */