As recently discussed on the list, btrfsck should only be run on unmounted filesystems. This patch adds a short check for the mount status at the beginning of btrfsck. If the FS is mounted, the program aborts showing an error message. Signed-off-by: Andi Drebes <lists-receive@programmierforen.de> --- diff --git a/btrfsck.c b/btrfsck.c index 73f1836..87ae776 100644 --- a/btrfsck.c +++ b/btrfsck.c @@ -28,6 +28,7 @@ #include "transaction.h" #include "list.h" #include "version.h" +#include "utils.h" static u64 bytes_used = 0; static u64 total_csum_bytes = 0; @@ -2819,6 +2820,16 @@ int main(int ac, char **av) if (ac < 2) print_usage(); + ret = check_mounted(av[1]); + if (ret < 0) { + fprintf(stderr, "error checking %s mount status\n", av[1]); + return 1; + } + if (ret == 1) { + fprintf(stderr, "%s is mounted. btrfsck can only be run on an unmounted filesystem.\n", av[1]); + return 1; + } + radix_tree_init(); cache_tree_init(&root_cache); root = open_ctree(av[1], 0, 0); -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Christoph Hellwig
2009-Oct-30 05:02 UTC
Re: [PATCH] Prevent btrfsck to run on mounted filesystems
On Thu, Oct 29, 2009 at 09:52:15PM +0100, Andi Drebes wrote:> As recently discussed on the list, btrfsck should only be run on unmounted filesystems. This patch adds a short check for the mount status at the beginning of btrfsck. If the FS is mounted, the program aborts showing an error message.Just open the nodes with O_EXCL and you''ll get all the checking for free. Also make sure that for a pure, read-only checks instead of a repair to allow running on at least a read-only mounted filesystem. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Chris Mason
2009-Oct-30 13:05 UTC
Re: [PATCH] Prevent btrfsck to run on mounted filesystems
On Fri, Oct 30, 2009 at 01:02:44AM -0400, Christoph Hellwig wrote:> On Thu, Oct 29, 2009 at 09:52:15PM +0100, Andi Drebes wrote: > > As recently discussed on the list, btrfsck should only be run on unmounted filesystems. This patch adds a short check for the mount status at the beginning of btrfsck. If the FS is mounted, the program aborts showing an error message. > > Just open the nodes with O_EXCL and you''ll get all the checking for > free. Also make sure that for a pure, read-only checks instead of a > repair to allow running on at least a read-only mounted filesystem. >Thanks for working on this patch Andi. In this case O_EXCL is going to be more accurate just because the mounted check doesn''t cover every disk in the FS. For now btrfsck doesn''t really give consistent results even readonly on a mounted filesystem. We should prevent it with a message just to prevent confusion. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Andi Drebes
2009-Oct-31 20:46 UTC
Re: [PATCH] Prevent btrfsck to run on mounted filesystems
> > Just open the nodes with O_EXCL and you''ll get all the checking for > > free. Also make sure that for a pure, read-only checks instead of a > > repair to allow running on at least a read-only mounted filesystem. > > Thanks for working on this patch Andi. > > In this case O_EXCL is going to be more accurate just because the > mounted check doesn''t cover every disk in the FS. For now btrfsck > doesn''t really give consistent results even readonly on a mounted > filesystem. We should prevent it with a message just to prevent > confusion.Thanks for the reply. I''ll do this as soon as I understand the code that is affected by those changes (I''m still in the learning phase and stepping through the code). Cheers, Andi -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Andi Drebes
2009-Nov-09 14:59 UTC
Re: [PATCH] Prevent btrfsck to run on mounted filesystems
Hi!> > In this case O_EXCL is going to be more accurate just because the > > mounted check doesn''t cover every disk in the FS. For now btrfsck > > doesn''t really give consistent results even readonly on a mounted > > filesystem. We should prevent it with a message just to prevent > > confusion. > Thanks for the reply. I''ll do this as soon as I understand the code > that is affected by those changes (I''m still in the learning phase > and stepping through the code).OK, I''ve stepped through the code so far and I think I now have an idea of what should be changed. However, concerning the solution, I was confusing two things. Christoph Hellwig earlier wrote:> Just open the nodes with O_EXCL and you''ll get all the checking for > free.I thought that open() with O_EXCL would fail if the file is already opened RW somewhere else. But the man page for open() says something else: "O_EXCL: Ensure that this call creates the file: if this flag is specified in conjunction with O_CREAT, and pathname already exists, then open() will fail." And especially: "The behavior of O_EXCL is undefined if O_CREAT is not specified." After having read this, I don''t see how this can help to prevent btrfsck to open a device that is mounted. What am I getting wrong? Currently, I would do the same check as in the original patch, but in btrfs_open_devices() instead of main(). Cheers, Andi -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html