[PATCH] btrfs-progs: specify mountpoint for recieve

[PATCH] btrfs-progs: specify mountpoint for recieve

[Josef Bacik]

In a chroot environment we may not have /proc mounted, which makes btrfs receive
freak out since it wants to know the base directory where are are mounted for
things like clone and such.  Give an option to specify where the mountpoint is
in these cases so you can still do a btrfs receive in a chroot.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
---
 cmds-receive.c | 47 +++++++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/cmds-receive.c b/cmds-receive.c
index b7cf3f9..28ae8e9 100644
--- a/cmds-receive.c
+++ b/cmds-receive.c
@@ -813,8 +813,8 @@ static struct btrfs_send_ops send_ops = {
 	.utimes = process_utimes,
 };
 
-static int do_receive(struct btrfs_receive *r, const char *tomnt, int r_fd,
-		      u64 max_errors)
+static int do_receive(struct btrfs_receive *r, const char *tomnt,
+		      char *realmnt, int r_fd, u64 max_errors)
 {
 	int ret;
 	char *dest_dir_full_path;
@@ -836,20 +836,24 @@ static int do_receive(struct btrfs_receive *r, const char *tomnt, int r_fd,
 		goto out;
 	}
 
-	ret = find_mount_root(dest_dir_full_path, &r->root_path);
-	if (ret < 0) {
-		fprintf(stderr,
-			"ERROR: failed to determine mount point for %s: %s\n",
-			dest_dir_full_path, strerror(-ret));
-		ret = -EINVAL;
-		goto out;
-	}
-	if (ret > 0) {
-		fprintf(stderr,
+	if (realmnt) {
+		r->root_path = realmnt;
+	} else {
+		ret = find_mount_root(dest_dir_full_path, &r->root_path);
+		if (ret < 0) {
+			fprintf(stderr,
+				"ERROR: failed to determine mount point for %s: %s\n",
+				dest_dir_full_path, strerror(-ret));
+			ret = -EINVAL;
+			goto out;
+		}
+		if (ret > 0) {
+			fprintf(stderr,
 			"ERROR: %s doesn't belong to btrfs mount point\n",
 			dest_dir_full_path);
-		ret = -EINVAL;
-		goto out;
+			ret = -EINVAL;
+			goto out;
+		}
 	}
 	r->mnt_fd = open(r->root_path, O_RDONLY | O_NOATIME);
 	if (r->mnt_fd < 0) {
@@ -943,6 +947,7 @@ int cmd_receive(int argc, char **argv)
 {
 	char *tomnt = NULL;
 	char *fromfile = NULL;
+	char *realmnt = NULL;
 	struct btrfs_receive r;
 	int receive_fd = fileno(stdin);
 	u64 max_errors = 1;
@@ -962,7 +967,7 @@ int cmd_receive(int argc, char **argv)
 			{ NULL, 0, NULL, 0 }
 		};
 
-		c = getopt_long(argc, argv, "Cevf:", long_opts, NULL);
+		c = getopt_long(argc, argv, "Cevf:m:", long_opts, NULL);
 		if (c < 0)
 			break;
 
@@ -982,6 +987,13 @@ int cmd_receive(int argc, char **argv)
 		case 'E':
 			max_errors = arg_strtou64(optarg);
 			break;
+		case 'm':
+			realmnt = strdup(optarg);
+			if (!realmnt) {
+				fprintf(stderr, "ERROR: couldn't allocate realmnt.\n");
+				return 1;
+			}
+			break;
 		case '?':
 		default:
 			fprintf(stderr, "ERROR: receive args invalid.\n");
@@ -1002,7 +1014,7 @@ int cmd_receive(int argc, char **argv)
 		}
 	}
 
-	ret = do_receive(&r, tomnt, receive_fd, max_errors);
+	ret = do_receive(&r, tomnt, realmnt, receive_fd, max_errors);
 
 	return !!ret;
 }
@@ -1032,5 +1044,8 @@ const char * const cmd_receive_usage[] = {
 	"--max-errors <N> Terminate as soon as N errors happened while",
 	"                 processing commands from the send stream.",
 	"                 Default value is 1. A value of 0 means no limit.",
+	"-m <mountpoint>  The root mount point of the destination fs.",
+	"                 If you do not have /proc use this to tell us where ",
+	"                 this file system is mounted.",
 	NULL
 };
-- 
1.8.3.1

Re: [PATCH] btrfs-progs: specify mountpoint for recieve

[David Sterba]

On Wed, May 27, 2015 at 01:51:29PM -0400, Josef Bacik wrote:
> In a chroot environment we may not have /proc mounted, which makes btrfs receive
> freak out since it wants to know the base directory where are are mounted for
> things like clone and such

Does this https://patchwork.kernel.org/patch/6456671/ fix the problem
with clones?

Re: [PATCH] btrfs-progs: specify mountpoint for recieve

[Josef Bacik]

On 05/28/2015 08:37 AM, David Sterba wrote:
> On Wed, May 27, 2015 at 01:51:29PM -0400, Josef Bacik wrote:
>> In a chroot environment we may not have /proc mounted, which makes btrfs receive
>> freak out since it wants to know the base directory where are are mounted for
>> things like clone and such
>
> Does this https://patchwork.kernel.org/patch/6456671/ fix the problem
> with clones?
>

So that patch is for using the -C option, which chroot's before doing a 
receive.  What I'm doing is when we're already in a chroot'ed 
environment, not using -C, so don't have access to /proc.  Thanks,

Josef

Re: [PATCH] btrfs-progs: specify mountpoint for recieve

[David Sterba]

On Wed, May 27, 2015 at 01:51:29PM -0400, Josef Bacik wrote:
> In a chroot environment we may not have /proc mounted, which makes btrfs receive
> freak out since it wants to know the base directory where are are mounted for
> things like clone and such.  Give an option to specify where the mountpoint is
> in these cases so you can still do a btrfs receive in a chroot.  Thanks,
> 
> Signed-off-by: Josef Bacik <jbacik@fb.com>

Applied, thanks.