LU-9859 libcfs: opencode cfs_cap_{raise,lower,raised}

Each of these functions is used precisely once, so having
a separate exported function seems like overkill.

cfs_cap_raised() is trivial - one line.
cfs_cap_raise() and cfs_cap_lower() are used as a pair
which is more effectively implemented with
override_cred() / revert_creds().

Linux-commit: cc738c1a69da27be8ff7885b4069fa02e45c75c1

There exists a bug in the original Linux client patch.
Additionally handling the SYS_CAP_RESOURCE is used
extensively with the server code so create we can create
simple inline functions that handle this and it makes
the code cleaner.

Change-Id: I3a39a855fb9718ca43e74ef4b9e749b0f43f4bc8
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: https://review.whamcloud.com/36304
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Shaun Tancheff <stancheff@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/libcfs/include/libcfs/curproc.h b/libcfs/include/libcfs/curproc.h
index 0f00c72..17ecd90 100644 (file)
--- a/libcfs/include/libcfs/curproc.h
+++ b/libcfs/include/libcfs/curproc.h
@@ -65,9 +65,6 @@ typedef __u32 cfs_cap_t;
                          (1 << CFS_CAP_SYS_BOOT) |              \
                          (1 << CFS_CAP_SYS_RESOURCE))
 
-void cfs_cap_raise(cfs_cap_t cap);
-void cfs_cap_lower(cfs_cap_t cap);
-int cfs_cap_raised(cfs_cap_t cap);
 cfs_cap_t cfs_curproc_cap_pack(void);
 void cfs_curproc_cap_unpack(cfs_cap_t cap);
 int cfs_capable(cfs_cap_t cap);

diff --git a/libcfs/libcfs/linux/linux-curproc.c b/libcfs/libcfs/linux/linux-curproc.c
index fee47a2..70510c9 100644 (file)
--- a/libcfs/libcfs/linux/linux-curproc.c
+++ b/libcfs/libcfs/linux/linux-curproc.c
@@ -59,29 +59,6 @@
 #define cfs_cap_pack(cap) (cap)
 #define cfs_cap_unpack(cap) (cap)
 
-void cfs_cap_raise(cfs_cap_t cap)
-{
-        struct cred *cred;
-        if ((cred = prepare_creds())) {
-                cap_raise(cred->cap_effective, cfs_cap_unpack(cap));
-                commit_creds(cred);
-        }
-}
-
-void cfs_cap_lower(cfs_cap_t cap)
-{
-        struct cred *cred;
-        if ((cred = prepare_creds())) {
-                cap_lower(cred->cap_effective, cfs_cap_unpack(cap));
-                commit_creds(cred);
-        }
-}
-
-int cfs_cap_raised(cfs_cap_t cap)
-{
-        return cap_raised(current_cap(), cfs_cap_unpack(cap));
-}
-
 static void cfs_kernel_cap_pack(kernel_cap_t kcap, cfs_cap_t *cap)
 {
 #if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
@@ -289,9 +266,6 @@ out:
 }
 EXPORT_SYMBOL(cfs_get_environ);
 
-EXPORT_SYMBOL(cfs_cap_raise);
-EXPORT_SYMBOL(cfs_cap_lower);
-EXPORT_SYMBOL(cfs_cap_raised);
 EXPORT_SYMBOL(cfs_curproc_cap_pack);
 EXPORT_SYMBOL(cfs_capable);
 

diff --git a/lustre/obdclass/llog.c b/lustre/obdclass/llog.c
index 43bf396..5ae88a2 100644 (file)
--- a/lustre/obdclass/llog.c
+++ b/lustre/obdclass/llog.c
@@ -828,6 +828,27 @@ int llog_process(const struct lu_env *env, struct llog_handle *loghandle,
 }
 EXPORT_SYMBOL(llog_process);
 
+static inline const struct cred *llog_raise_resource(void)
+{
+       struct cred *cred = NULL;
+
+       if (cap_raised(current_cap(), CAP_SYS_RESOURCE))
+               return cred;
+
+       cred = prepare_creds();
+       if (!cred)
+               return cred;
+
+       cap_raise(cred->cap_effective, CAP_SYS_RESOURCE);
+       return override_creds(cred);
+}
+
+static inline void llog_restore_resource(const struct cred *old_cred)
+{
+       if (old_cred)
+               revert_creds(old_cred);
+}
+
 int llog_reverse_process(const struct lu_env *env,
                         struct llog_handle *loghandle, llog_cb_t cb,
                         void *data, void *catdata)
@@ -952,8 +973,9 @@ EXPORT_SYMBOL(llog_exist);
 int llog_declare_create(const struct lu_env *env,
                        struct llog_handle *loghandle, struct thandle *th)
 {
+       const struct cred *old_cred;
        struct llog_operations  *lop;
-       int                      raised, rc;
+       int rc;
 
        ENTRY;
 
@@ -963,20 +985,18 @@ int llog_declare_create(const struct lu_env *env,
        if (lop->lop_declare_create == NULL)
                RETURN(-EOPNOTSUPP);
 
-       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
-       if (!raised)
-               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       old_cred = llog_raise_resource();
        rc = lop->lop_declare_create(env, loghandle, th);
-       if (!raised)
-               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       llog_restore_resource(old_cred);
        RETURN(rc);
 }
 
 int llog_create(const struct lu_env *env, struct llog_handle *handle,
                struct thandle *th)
 {
+       const struct cred *old_cred;
        struct llog_operations  *lop;
-       int                      raised, rc;
+       int rc;
 
        ENTRY;
 
@@ -986,12 +1006,9 @@ int llog_create(const struct lu_env *env, struct llog_handle *handle,
        if (lop->lop_create == NULL)
                RETURN(-EOPNOTSUPP);
 
-       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
-       if (!raised)
-               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       old_cred = llog_raise_resource();
        rc = lop->lop_create(env, handle, th);
-       if (!raised)
-               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       llog_restore_resource(old_cred);
        RETURN(rc);
 }
 
@@ -1000,8 +1017,9 @@ int llog_declare_write_rec(const struct lu_env *env,
                           struct llog_rec_hdr *rec, int idx,
                           struct thandle *th)
 {
+       const struct cred *old_cred;
        struct llog_operations  *lop;
-       int                      raised, rc;
+       int rc;
 
        ENTRY;
 
@@ -1012,12 +1030,9 @@ int llog_declare_write_rec(const struct lu_env *env,
        if (lop->lop_declare_write_rec == NULL)
                RETURN(-EOPNOTSUPP);
 
-       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
-       if (!raised)
-               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       old_cred = llog_raise_resource();
        rc = lop->lop_declare_write_rec(env, handle, rec, idx, th);
-       if (!raised)
-               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       llog_restore_resource(old_cred);
        RETURN(rc);
 }
 
@@ -1025,8 +1040,9 @@ int llog_write_rec(const struct lu_env *env, struct llog_handle *handle,
                   struct llog_rec_hdr *rec, struct llog_cookie *logcookies,
                   int idx, struct thandle *th)
 {
+       const struct cred *old_cred;
        struct llog_operations  *lop;
-       int                      raised, rc, buflen;
+       int rc, buflen;
 
        ENTRY;
 
@@ -1059,12 +1075,9 @@ int llog_write_rec(const struct lu_env *env, struct llog_handle *handle,
        buflen = rec->lrh_len;
        LASSERT(cfs_size_round(buflen) == buflen);
 
-       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
-       if (!raised)
-               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       old_cred = llog_raise_resource();
        rc = lop->lop_write_rec(env, handle, rec, logcookies, idx, th);
-       if (!raised)
-               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       llog_restore_resource(old_cred);
        RETURN(rc);
 }
 
@@ -1072,19 +1085,17 @@ int llog_add(const struct lu_env *env, struct llog_handle *lgh,
             struct llog_rec_hdr *rec, struct llog_cookie *logcookies,
             struct thandle *th)
 {
-       int raised, rc;
+       const struct cred *old_cred;
+       int rc;
 
        ENTRY;
 
        if (lgh->lgh_logops->lop_add == NULL)
                RETURN(-EOPNOTSUPP);
 
-       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
-       if (!raised)
-               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       old_cred = llog_raise_resource();
        rc = lgh->lgh_logops->lop_add(env, lgh, rec, logcookies, th);
-       if (!raised)
-               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       llog_restore_resource(old_cred);
        RETURN(rc);
 }
 EXPORT_SYMBOL(llog_add);
@@ -1092,19 +1103,17 @@ EXPORT_SYMBOL(llog_add);
 int llog_declare_add(const struct lu_env *env, struct llog_handle *lgh,
                     struct llog_rec_hdr *rec, struct thandle *th)
 {
-       int raised, rc;
+       const struct cred *old_cred;
+       int rc;
 
        ENTRY;
 
        if (lgh->lgh_logops->lop_declare_add == NULL)
                RETURN(-EOPNOTSUPP);
 
-       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
-       if (!raised)
-               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       old_cred = llog_raise_resource();
        rc = lgh->lgh_logops->lop_declare_add(env, lgh, rec, th);
-       if (!raised)
-               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       llog_restore_resource(old_cred);
        RETURN(rc);
 }
 EXPORT_SYMBOL(llog_declare_add);
@@ -1257,7 +1266,7 @@ int llog_open(const struct lu_env *env, struct llog_ctxt *ctxt,
              struct llog_handle **lgh, struct llog_logid *logid,
              char *name, enum llog_open_param open_param)
 {
-       int      raised;
+       const struct cred *old_cred;
        int      rc;
 
        ENTRY;
@@ -1276,12 +1285,9 @@ int llog_open(const struct lu_env *env, struct llog_ctxt *ctxt,
        (*lgh)->lgh_ctxt = ctxt;
        (*lgh)->lgh_logops = ctxt->loc_logops;
 
-       raised = cfs_cap_raised(CFS_CAP_SYS_RESOURCE);
-       if (!raised)
-               cfs_cap_raise(CFS_CAP_SYS_RESOURCE);
+       old_cred = llog_raise_resource();
        rc = ctxt->loc_logops->lop_open(env, *lgh, logid, name, open_param);
-       if (!raised)
-               cfs_cap_lower(CFS_CAP_SYS_RESOURCE);
+       llog_restore_resource(old_cred);
        if (rc) {
                llog_free_handle(*lgh);
                *lgh = NULL;