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authorLennart Poettering <lennart@poettering.net>2016-10-25 11:39:09 +0200
committerLennart Poettering <lennart@poettering.net>2016-11-02 11:39:49 -0600
commit2bce2acce869686d4417fa679eb794b5dc873110 (patch)
treef83190091b1ee8ab895c550648375fa7113e2011 /src/nspawn
parentb5d7f1bbfa09f2713d72f76f89d2f830e382382b (diff)
nspawn: if we set up a loopback device, try to mount it with "discard"
Let's make sure that our loopback files remain sparse, hence let's set "discard" as mount option on file systems that support it if the backing device is a loopback.
Diffstat (limited to 'src/nspawn')
-rw-r--r--src/nspawn/nspawn.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 295293858e..c56af6e6f4 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -2260,7 +2260,7 @@ static int dissect_image(
static int mount_device(const char *what, const char *where, const char *directory, bool rw) {
#ifdef HAVE_BLKID
_cleanup_blkid_free_probe_ blkid_probe b = NULL;
- const char *fstype, *p;
+ const char *fstype, *p, *options;
int r;
assert(what);
@@ -2309,7 +2309,17 @@ static int mount_device(const char *what, const char *where, const char *directo
return -EOPNOTSUPP;
}
- return mount_verbose(LOG_ERR, what, p, fstype, MS_NODEV|(rw ? 0 : MS_RDONLY), NULL);
+ /* If this is a loopback device then let's mount the image with discard, so that the underlying file remains
+ * sparse when possible. */
+ if (STR_IN_SET(fstype, "btrfs", "ext4", "vfat", "xfs")) {
+ const char *l;
+
+ l = path_startswith(what, "/dev");
+ if (l && startswith(l, "loop"))
+ options = "discard";
+ }
+
+ return mount_verbose(LOG_ERR, what, p, fstype, MS_NODEV|(rw ? 0 : MS_RDONLY), options);
#else
log_error("--image= is not supported, compiled without blkid support.");
return -EOPNOTSUPP;