| Message ID | 20250130-work-mnt_idmap-statmount-v1-3-d4ced5874e14@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | statmount: allow to retrieve idmappings | expand |
On Thu, 30 Jan 2025 at 00:20, Christian Brauner <brauner@kernel.org> wrote: > > For string options the kernel will raise the corresponding flag only if > the string isn't empty. So check for the flag. Hmm, seems like this is going to be a common mistake. How about just putting a nul char at sm->str, which will solve this once and for all (any unset str_ offset will point to this empty string)? Then we can say that instead of checking the mask for a string it's okay to rely on it being empty by default. Thanks, Miklos
On Thu, Jan 30, 2025 at 09:45:50AM +0100, Miklos Szeredi wrote: > On Thu, 30 Jan 2025 at 00:20, Christian Brauner <brauner@kernel.org> wrote: > > > > For string options the kernel will raise the corresponding flag only if > > the string isn't empty. So check for the flag. > > Hmm, seems like this is going to be a common mistake. Probably. > > How about just putting a nul char at sm->str, which will solve this > once and for all (any unset str_ offset will point to this empty > string)? Agreed. > > Then we can say that instead of checking the mask for a string it's > okay to rely on it being empty by default. Right, but I do prefer checking whether the flag is raised or not. But we can just support both.
diff --git a/samples/vfs/test-list-all-mounts.c b/samples/vfs/test-list-all-mounts.c index 1a02ea4593e3..ce272ded8a79 100644 --- a/samples/vfs/test-list-all-mounts.c +++ b/samples/vfs/test-list-all-mounts.c @@ -138,10 +138,11 @@ int main(int argc, char *argv[]) printf("mnt_id:\t\t%" PRIu64 "\nmnt_parent_id:\t%" PRIu64 "\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n\n", (uint64_t)stmnt->mnt_id, (uint64_t)stmnt->mnt_parent_id, - stmnt->str + stmnt->fs_type, - stmnt->str + stmnt->mnt_root, - stmnt->str + stmnt->mnt_point, - stmnt->str + stmnt->mnt_opts); + (stmnt->mask & STATMOUNT_FS_TYPE) ? stmnt->str + stmnt->fs_type : "", + (stmnt->mask & STATMOUNT_MNT_ROOT) ? stmnt->str + stmnt->mnt_root : "", + (stmnt->mask & STATMOUNT_MNT_POINT) ? stmnt->str + stmnt->mnt_point : "", + (stmnt->mask & STATMOUNT_MNT_OPTS) ? stmnt->str + stmnt->mnt_opts : ""); + free(stmnt); } }
For string options the kernel will raise the corresponding flag only if the string isn't empty. So check for the flag. Signed-off-by: Christian Brauner <brauner@kernel.org> --- samples/vfs/test-list-all-mounts.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)