expose snapshot count via stat(2) of .zfs/snapshot (#13559)

Increase nlinks in stat results of ./zfs/snapshot based on snapshot
count. This provides quick and efficient method for administrators to
get snapshot counts without having to use libzfs or list the snapdir
contents.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Andrew Walker <awalker@ixsystems.com>
Closes #13559
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Andrew 2022-06-17 13:44:49 -05:00 committed by GitHub
parent 10891b37fa
commit f609739985
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@ -32,6 +32,9 @@
#include <sys/zfs_vnops.h> #include <sys/zfs_vnops.h>
#include <sys/zfs_ctldir.h> #include <sys/zfs_ctldir.h>
#include <sys/zpl.h> #include <sys/zpl.h>
#include <sys/dmu.h>
#include <sys/dsl_dataset.h>
#include <sys/zap.h>
/* /*
* Common open routine. Disallow any write access. * Common open routine. Disallow any write access.
@ -411,6 +414,20 @@ zpl_snapdir_getattr_impl(const struct path *path, struct kstat *stat,
#endif #endif
stat->nlink = stat->size = 2; stat->nlink = stat->size = 2;
dsl_dataset_t *ds = dmu_objset_ds(zfsvfs->z_os);
if (dsl_dataset_phys(ds)->ds_snapnames_zapobj != 0) {
uint64_t snap_count;
int err = zap_count(
dmu_objset_pool(ds->ds_objset)->dp_meta_objset,
dsl_dataset_phys(ds)->ds_snapnames_zapobj, &snap_count);
if (err != 0) {
ZPL_EXIT(zfsvfs);
return (-err);
}
stat->nlink += snap_count;
}
stat->ctime = stat->mtime = dmu_objset_snap_cmtime(zfsvfs->z_os); stat->ctime = stat->mtime = dmu_objset_snap_cmtime(zfsvfs->z_os);
stat->atime = current_time(ip); stat->atime = current_time(ip);
ZPL_EXIT(zfsvfs); ZPL_EXIT(zfsvfs);