[PATCH] rmcp: print sensible error message on permission failure

[Dan McGee <dan-fd97jBR+K/6hPH1hqNUYSQ@public.gmane.org>]

When running as non-root, the error message seems to indicate a
checkpoint is a snapshot, rather than the actual problem, which is that
I do not have permission to delete the checkpoints.

Before:
    $ rmcp 29..35
    rmcp: 29: cannot remove snapshot
    rmcp: 30: cannot remove snapshot
    rmcp: 31: cannot remove snapshot
    rmcp: 32: cannot remove snapshot
    rmcp: 33: cannot remove snapshot
    rmcp: 34: cannot remove snapshot
    rmcp: 35: cannot remove snapshot

    To delete snapshot(s), change them into checkpoints with
    chcp command before removal.

After:
    $ ./bin/rmcp 29..35
    lt-rmcp: 29: cannot remove checkpoint: Operation not permitted
    Remaining checkpoints were not removed.

Since May 2009 the kernel has returned EBUSY instead of EPERM for
removal requests against snapshots, commit 30c25be71fcbd87fd. We should
be able to treat EPERM as expected now, as the commit message there
indicates.

Signed-off-by: Dan McGee <dan-fd97jBR+K/6hPH1hqNUYSQ@public.gmane.org>
---
 bin/rmcp.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/bin/rmcp.c b/bin/rmcp.c
index 780a192..9f4666a 100644
--- a/bin/rmcp.c
+++ b/bin/rmcp.c
@@ -105,7 +105,7 @@ static int rmcp_remove_range(struct nilfs *nilfs,
 			nd++;
 			continue;
 		}
-		if (errno == EBUSY || errno == EPERM) {
+		if (errno == EBUSY) {
 			nss++;
 			if (!force) {
 				fprintf(stderr,
@@ -115,7 +115,10 @@ static int rmcp_remove_range(struct nilfs *nilfs,
 		} else if (errno == ENOENT) {
 			nocp++;
 		} else {
-			fprintf(stderr, "%s: %s\n", progname, strerror(errno));
+			fprintf(stderr,
+				"%s: %llu: cannot remove checkpoint: %s\n",
+				progname, (unsigned long long)cno,
+				strerror(errno));
 			ret = -1;
 			goto out;
 		}
@@ -237,8 +240,10 @@ int main(int argc, char *argv[])
 			continue;
 
 		status = 1;
-		if (ret < 0)
+		if (ret < 0) {
+			fprintf(stderr, "Remaining checkpoints were not removed.\n");
 			break;
+		}
 
 		if (force || ndel != 0 || end - start + 1 - nss == 0)
 			continue;
-- 
1.7.8.1

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