From 81f0a57bed6e03eeaa24443d16555c7f5d20ee1a Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Wed, 22 Apr 2015 13:08:19 +0200

Subject: [PATCH] btrfs-util: introduce btrfs_is_filesystem() and make use of

 it where appropriate

Let's unify the code that checks whether an fd is on btrfs a bit.

(Also, rename btrfs_is_snapshot() to btrfs_is_subvol(), since that's

usually how this is referred to in our code)

(cherry picked from commit 21222ea5cdec65fa30a75bd5a78475459075b946)

Related: #1299714

---

 src/shared/btrfs-util.c    | 23 ++++++++++++++++-------

 src/shared/btrfs-util.h    |  3 ++-

 src/shared/machine-image.c |  9 ++++-----

 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/src/shared/btrfs-util.c b/src/shared/btrfs-util.c

index b34ac8b15..52a214349 100644

--- a/src/shared/btrfs-util.c

+++ b/src/shared/btrfs-util.c

@@ -83,10 +83,22 @@ static int extract_subvolume_name(const char *path, const char **subvolume) {

         return 0;

 }

-int btrfs_is_snapshot(int fd) {

-        struct stat st;

+int btrfs_is_filesystem(int fd) {

         struct statfs sfs;

+        assert(fd >= 0);

+

+        if (fstatfs(fd, &sfs) < 0)

+                return -errno;

+

+        return F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC);

+}

+

+int btrfs_is_subvol(int fd) {

+        struct stat st;

+

+        assert(fd >= 0);

+

         /* On btrfs subvolumes always have the inode 256 */

         if (fstat(fd, &st) < 0)

@@ -95,10 +107,7 @@ int btrfs_is_snapshot(int fd) {

         if (!S_ISDIR(st.st_mode) || st.st_ino != 256)

                 return 0;

-        if (fstatfs(fd, &sfs) < 0)

-                return -errno;

-

-        return F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC);

+        return btrfs_is_filesystem(fd);

 }

 int btrfs_subvol_snapshot(const char *old_path, const char *new_path, bool read_only, bool fallback_copy) {

@@ -115,7 +124,7 @@ int btrfs_subvol_snapshot(const char *old_path, const char *new_path, bool read_

         if (old_fd < 0)

                 return -errno;

-        r = btrfs_is_snapshot(old_fd);

+        r = btrfs_is_subvol(old_fd);

         if (r < 0)

                 return r;

         if (r == 0) {

diff --git a/src/shared/btrfs-util.h b/src/shared/btrfs-util.h

index 1b9c142e5..1315def87 100644

--- a/src/shared/btrfs-util.h

+++ b/src/shared/btrfs-util.h

@@ -43,7 +43,8 @@ typedef struct BtrfsQuotaInfo {

         uint64_t exclusive_max;

 } BtrfsQuotaInfo;

-int btrfs_is_snapshot(int fd);

+int btrfs_is_filesystem(int fd);

+int btrfs_is_subvol(int fd);

 int btrfs_subvol_make(const char *path);

 int btrfs_subvol_make_label(const char *path);

diff --git a/src/shared/machine-image.c b/src/shared/machine-image.c

index c02ee814c..256622928 100644

--- a/src/shared/machine-image.c

+++ b/src/shared/machine-image.c

@@ -136,12 +136,11 @@ static int image_make(

                 /* btrfs subvolumes have inode 256 */

                 if (st.st_ino == 256) {

-                        struct statfs sfs;

-                        if (fstatfs(fd, &sfs) < 0)

-                                return -errno;

-

-                        if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC)) {

+                        r = btrfs_is_filesystem(fd);

+                        if (r < 0)

+                                return r;

+                        if (r) {

                                 BtrfsSubvolInfo info;

                                 BtrfsQuotaInfo quota;