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81895a65ec
linux/fs/ceph/mdsmap.c
Jason A. Donenfeld 81895a65ec treewide: use prandom_u32_max() when possible, part 1 
Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:

@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)

@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@

-       RAND = get_random_u32();
        ... when != RAND
-       RAND %= (E);
+       RAND = prandom_u32_max(E);

// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@

        ((T)get_random_u32()@p & (LITERAL))

// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@

value = None
if literal.startswith('0x'):
        value = int(literal, 16)
elif literal[0] in '123456789':
        value = int(literal, 10)
if value is None:
        print("I don't know how to handle %s" % (literal))
        cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
        print("Skipping 0x%x for cleanup elsewhere" % (value))
        cocci.include_match(False)
elif value & (value + 1) != 0:
        print("Skipping 0x%x because it's not a power of two minus one" % (value))
        cocci.include_match(False)
elif literal.startswith('0x'):
        coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
        coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))

// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@

-       (FUNC()@p & (LITERAL))
+       prandom_u32_max(RESULT)

@collapse_ret@
type T;
identifier VAR;
expression E;
@@

 {
-       T VAR;
-       VAR = (E);
-       return VAR;
+       return E;
 }

@drop_var@
type T;
identifier VAR;
@@

 {
-       T VAR;
        ... when != VAR
 }

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-10-11 17:42:55 -06:00

437 lines
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// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>
#include <linux/bug.h>
#include <linux/err.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/ceph/mdsmap.h>
#include <linux/ceph/messenger.h>
#include <linux/ceph/decode.h>
#include "super.h"
#define CEPH_MDS_IS_READY(i, ignore_laggy) \
(m->m_info[i].state > 0 && ignore_laggy ? true : !m->m_info[i].laggy)
static int __mdsmap_get_random_mds(struct ceph_mdsmap *m, bool ignore_laggy)
{
int n = 0;
int i, j;
/* count */
for (i = 0; i < m->possible_max_rank; i++)
if (CEPH_MDS_IS_READY(i, ignore_laggy))
n++;
if (n == 0)
return -1;
/* pick */
n = prandom_u32_max(n);
for (j = 0, i = 0; i < m->possible_max_rank; i++) {
if (CEPH_MDS_IS_READY(i, ignore_laggy))
j++;
if (j > n)
break;
}
return i;
}
/*
* choose a random mds that is "up" (i.e. has a state > 0), or -1.
*/
int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m)
{
int mds;
mds = __mdsmap_get_random_mds(m, false);
if (mds == m->possible_max_rank || mds == -1)
mds = __mdsmap_get_random_mds(m, true);
return mds == m->possible_max_rank ? -1 : mds;
}
#define __decode_and_drop_type(p, end, type, bad) \
do { \
if (*p + sizeof(type) > end) \
goto bad; \
*p += sizeof(type); \
} while (0)
#define __decode_and_drop_set(p, end, type, bad) \
do { \
u32 n; \
size_t need; \
ceph_decode_32_safe(p, end, n, bad); \
need = sizeof(type) * n; \
ceph_decode_need(p, end, need, bad); \
*p += need; \
} while (0)
#define __decode_and_drop_map(p, end, ktype, vtype, bad) \
do { \
u32 n; \
size_t need; \
ceph_decode_32_safe(p, end, n, bad); \
need = (sizeof(ktype) + sizeof(vtype)) * n; \
ceph_decode_need(p, end, need, bad); \
*p += need; \
} while (0)
static int __decode_and_drop_compat_set(void **p, void* end)
{
int i;
/* compat, ro_compat, incompat*/
for (i = 0; i < 3; i++) {
u32 n;
ceph_decode_need(p, end, sizeof(u64) + sizeof(u32), bad);
/* mask */
*p += sizeof(u64);
/* names (map<u64, string>) */
n = ceph_decode_32(p);
while (n-- > 0) {
u32 len;
ceph_decode_need(p, end, sizeof(u64) + sizeof(u32),
bad);
*p += sizeof(u64);
len = ceph_decode_32(p);
ceph_decode_need(p, end, len, bad);
*p += len;
}
}
return 0;
bad:
return -1;
}
/*
* Decode an MDS map
*
* Ignore any fields we don't care about (there are quite a few of
* them).
*/
struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2)
{
struct ceph_mdsmap *m;
const void *start = *p;
int i, j, n;
int err;
u8 mdsmap_v;
u16 mdsmap_ev;
u32 target;
m = kzalloc(sizeof(*m), GFP_NOFS);
if (!m)
return ERR_PTR(-ENOMEM);
ceph_decode_need(p, end, 1 + 1, bad);
mdsmap_v = ceph_decode_8(p);
*p += sizeof(u8); /* mdsmap_cv */
if (mdsmap_v >= 4) {
u32 mdsmap_len;
ceph_decode_32_safe(p, end, mdsmap_len, bad);
if (end < *p + mdsmap_len)
goto bad;
end = *p + mdsmap_len;
}
ceph_decode_need(p, end, 8*sizeof(u32) + sizeof(u64), bad);
m->m_epoch = ceph_decode_32(p);
m->m_client_epoch = ceph_decode_32(p);
m->m_last_failure = ceph_decode_32(p);
m->m_root = ceph_decode_32(p);
m->m_session_timeout = ceph_decode_32(p);
m->m_session_autoclose = ceph_decode_32(p);
m->m_max_file_size = ceph_decode_64(p);
m->m_max_mds = ceph_decode_32(p);
/*
* pick out the active nodes as the m_num_active_mds, the
* m_num_active_mds maybe larger than m_max_mds when decreasing
* the max_mds in cluster side, in other case it should less
* than or equal to m_max_mds.
*/
m->m_num_active_mds = n = ceph_decode_32(p);
/*
* the possible max rank, it maybe larger than the m_num_active_mds,
* for example if the mds_max == 2 in the cluster, when the MDS(0)
* was laggy and being replaced by a new MDS, we will temporarily
* receive a new mds map with n_num_mds == 1 and the active MDS(1),
* and the mds rank >= m_num_active_mds.
*/
m->possible_max_rank = max(m->m_num_active_mds, m->m_max_mds);
m->m_info = kcalloc(m->possible_max_rank, sizeof(*m->m_info), GFP_NOFS);
if (!m->m_info)
goto nomem;
/* pick out active nodes from mds_info (state > 0) */
for (i = 0; i < n; i++) {
u64 global_id;
u32 namelen;
s32 mds, inc, state;
u8 info_v;
void *info_end = NULL;
struct ceph_entity_addr addr;
u32 num_export_targets;
void *pexport_targets = NULL;
struct ceph_timespec laggy_since;
struct ceph_mds_info *info;
bool laggy;
ceph_decode_need(p, end, sizeof(u64) + 1, bad);
global_id = ceph_decode_64(p);
info_v= ceph_decode_8(p);
if (info_v >= 4) {
u32 info_len;
ceph_decode_need(p, end, 1 + sizeof(u32), bad);
*p += sizeof(u8); /* info_cv */
info_len = ceph_decode_32(p);
info_end = *p + info_len;
if (info_end > end)
goto bad;
}
ceph_decode_need(p, end, sizeof(u64) + sizeof(u32), bad);
*p += sizeof(u64);
namelen = ceph_decode_32(p); /* skip mds name */
*p += namelen;
ceph_decode_32_safe(p, end, mds, bad);
ceph_decode_32_safe(p, end, inc, bad);
ceph_decode_32_safe(p, end, state, bad);
*p += sizeof(u64); /* state_seq */
if (info_v >= 8)
err = ceph_decode_entity_addrvec(p, end, msgr2, &addr);
else
err = ceph_decode_entity_addr(p, end, &addr);
if (err)
goto corrupt;
ceph_decode_copy_safe(p, end, &laggy_since, sizeof(laggy_since),
bad);
laggy = laggy_since.tv_sec != 0 || laggy_since.tv_nsec != 0;
*p += sizeof(u32);
ceph_decode_32_safe(p, end, namelen, bad);
*p += namelen;
if (info_v >= 2) {
ceph_decode_32_safe(p, end, num_export_targets, bad);
pexport_targets = *p;
*p += num_export_targets * sizeof(u32);
} else {
num_export_targets = 0;
}
if (info_end && *p != info_end) {
if (*p > info_end)
goto bad;
*p = info_end;
}
dout("mdsmap_decode %d/%d %lld mds%d.%d %s %s%s\n",
i+1, n, global_id, mds, inc,
ceph_pr_addr(&addr),
ceph_mds_state_name(state),
laggy ? "(laggy)" : "");
if (mds < 0 || mds >= m->possible_max_rank) {
pr_warn("mdsmap_decode got incorrect mds(%d)\n", mds);
continue;
}
if (state <= 0) {
dout("mdsmap_decode got incorrect state(%s)\n",
ceph_mds_state_name(state));
continue;
}
info = &m->m_info[mds];
info->global_id = global_id;
info->state = state;
info->addr = addr;
info->laggy = laggy;
info->num_export_targets = num_export_targets;
if (num_export_targets) {
info->export_targets = kcalloc(num_export_targets,
sizeof(u32), GFP_NOFS);
if (!info->export_targets)
goto nomem;
for (j = 0; j < num_export_targets; j++) {
target = ceph_decode_32(&pexport_targets);
info->export_targets[j] = target;
}
} else {
info->export_targets = NULL;
}
}
/* pg_pools */
ceph_decode_32_safe(p, end, n, bad);
m->m_num_data_pg_pools = n;
m->m_data_pg_pools = kcalloc(n, sizeof(u64), GFP_NOFS);
if (!m->m_data_pg_pools)
goto nomem;
ceph_decode_need(p, end, sizeof(u64)*(n+1), bad);
for (i = 0; i < n; i++)
m->m_data_pg_pools[i] = ceph_decode_64(p);
m->m_cas_pg_pool = ceph_decode_64(p);
m->m_enabled = m->m_epoch > 1;
mdsmap_ev = 1;
if (mdsmap_v >= 2) {
ceph_decode_16_safe(p, end, mdsmap_ev, bad_ext);
}
if (mdsmap_ev >= 3) {
if (__decode_and_drop_compat_set(p, end) < 0)
goto bad_ext;
}
/* metadata_pool */
if (mdsmap_ev < 5) {
__decode_and_drop_type(p, end, u32, bad_ext);
} else {
__decode_and_drop_type(p, end, u64, bad_ext);
}
/* created + modified + tableserver */
__decode_and_drop_type(p, end, struct ceph_timespec, bad_ext);
__decode_and_drop_type(p, end, struct ceph_timespec, bad_ext);
__decode_and_drop_type(p, end, u32, bad_ext);
/* in */
{
int num_laggy = 0;
ceph_decode_32_safe(p, end, n, bad_ext);
ceph_decode_need(p, end, sizeof(u32) * n, bad_ext);
for (i = 0; i < n; i++) {
s32 mds = ceph_decode_32(p);
if (mds >= 0 && mds < m->possible_max_rank) {
if (m->m_info[mds].laggy)
num_laggy++;
}
}
m->m_num_laggy = num_laggy;
if (n > m->possible_max_rank) {
void *new_m_info = krealloc(m->m_info,
n * sizeof(*m->m_info),
GFP_NOFS | __GFP_ZERO);
if (!new_m_info)
goto nomem;
m->m_info = new_m_info;
}
m->possible_max_rank = n;
}
/* inc */
__decode_and_drop_map(p, end, u32, u32, bad_ext);
/* up */
__decode_and_drop_map(p, end, u32, u64, bad_ext);
/* failed */
__decode_and_drop_set(p, end, u32, bad_ext);
/* stopped */
__decode_and_drop_set(p, end, u32, bad_ext);
if (mdsmap_ev >= 4) {
/* last_failure_osd_epoch */
__decode_and_drop_type(p, end, u32, bad_ext);
}
if (mdsmap_ev >= 6) {
/* ever_allowed_snaps */
__decode_and_drop_type(p, end, u8, bad_ext);
/* explicitly_allowed_snaps */
__decode_and_drop_type(p, end, u8, bad_ext);
}
if (mdsmap_ev >= 7) {
/* inline_data_enabled */
__decode_and_drop_type(p, end, u8, bad_ext);
}
if (mdsmap_ev >= 8) {
/* enabled */
ceph_decode_8_safe(p, end, m->m_enabled, bad_ext);
/* fs_name */
ceph_decode_skip_string(p, end, bad_ext);
}
/* damaged */
if (mdsmap_ev >= 9) {
size_t need;
ceph_decode_32_safe(p, end, n, bad_ext);
need = sizeof(u32) * n;
ceph_decode_need(p, end, need, bad_ext);
*p += need;
m->m_damaged = n > 0;
} else {
m->m_damaged = false;
}
if (mdsmap_ev >= 17) {
/* balancer */
ceph_decode_skip_string(p, end, bad_ext);
/* standby_count_wanted */
ceph_decode_skip_32(p, end, bad_ext);
/* old_max_mds */
ceph_decode_skip_32(p, end, bad_ext);
/* min_compat_client */
ceph_decode_skip_8(p, end, bad_ext);
/* required_client_features */
ceph_decode_skip_set(p, end, 64, bad_ext);
ceph_decode_64_safe(p, end, m->m_max_xattr_size, bad_ext);
} else {
/* This forces the usage of the (sync) SETXATTR Op */
m->m_max_xattr_size = 0;
}
bad_ext:
dout("mdsmap_decode m_enabled: %d, m_damaged: %d, m_num_laggy: %d\n",
!!m->m_enabled, !!m->m_damaged, m->m_num_laggy);
*p = end;
dout("mdsmap_decode success epoch %u\n", m->m_epoch);
return m;
nomem:
err = -ENOMEM;
goto out_err;
corrupt:
pr_err("corrupt mdsmap\n");
print_hex_dump(KERN_DEBUG, "mdsmap: ",
DUMP_PREFIX_OFFSET, 16, 1,
start, end - start, true);
out_err:
ceph_mdsmap_destroy(m);
return ERR_PTR(err);
bad:
err = -EINVAL;
goto corrupt;
}
void ceph_mdsmap_destroy(struct ceph_mdsmap *m)
{
int i;
if (m->m_info) {
for (i = 0; i < m->possible_max_rank; i++)
kfree(m->m_info[i].export_targets);
kfree(m->m_info);
}
kfree(m->m_data_pg_pools);
kfree(m);
}
bool ceph_mdsmap_is_cluster_available(struct ceph_mdsmap *m)
{
int i, nr_active = 0;
if (!m->m_enabled)
return false;
if (m->m_damaged)
return false;
if (m->m_num_laggy == m->m_num_active_mds)
return false;
for (i = 0; i < m->possible_max_rank; i++) {
if (m->m_info[i].state == CEPH_MDS_STATE_ACTIVE)
nr_active++;
}
return nr_active > 0;
}
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