From 5bebf7486d4f4940b2a8e4009beb1dff5041853d Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 1 Feb 2020 22:42:31 +0800 Subject: bcache: fix memory corruption in bch_cache_accounting_clear() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 83ff9318c44ba ("bcache: not use hard coded memset size in bch_cache_accounting_clear()") tries to make the code more easy to understand by removing the hard coded number with following change, void bch_cache_accounting_clear(...) { memset(&acc->total.cache_hits, 0, - sizeof(unsigned long) * 7); + sizeof(struct cache_stats)); } Unfortunately the change was wrong (it also tells us the original code was not easy to correctly understand). The hard coded number 7 is used because in struct cache_stats, 15 struct cache_stats { 16 struct kobject kobj; 17 18 unsigned long cache_hits; 19 unsigned long cache_misses; 20 unsigned long cache_bypass_hits; 21 unsigned long cache_bypass_misses; 22 unsigned long cache_readaheads; 23 unsigned long cache_miss_collisions; 24 unsigned long sectors_bypassed; 25 26 unsigned int rescale; 27 }; only members in LINE 18-24 want to be set to 0. It is wrong to use 'sizeof(struct cache_stats)' to replace 'sizeof(unsigned long) * 7), the memory objects behind acc->total is staled by this change. Сорокин Артем Сергеевич reports that by the following steps, kernel panic will be triggered, 1. Create new set: make-bcache -B /dev/nvme1n1 -C /dev/sda --wipe-bcache 2. Run in /sys/fs/bcache/: echo 1 > clear_stats && cat stats_five_minute/cache_bypass_hits I can reproduce the panic and get following dmesg with KASAN enabled, [22613.172742] ================================================================== [22613.172862] BUG: KASAN: null-ptr-deref in sysfs_kf_seq_show+0x117/0x230 [22613.172864] Read of size 8 at addr 0000000000000000 by task cat/6753 [22613.172870] CPU: 1 PID: 6753 Comm: cat Not tainted 5.5.0-rc7-lp151.28.16-default+ #11 [22613.172872] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/29/2019 [22613.172873] Call Trace: [22613.172964] dump_stack+0x8b/0xbb [22613.172968] ? sysfs_kf_seq_show+0x117/0x230 [22613.172970] ? sysfs_kf_seq_show+0x117/0x230 [22613.173031] __kasan_report+0x176/0x192 [22613.173064] ? pr_cont_kernfs_name+0x40/0x60 [22613.173067] ? sysfs_kf_seq_show+0x117/0x230 [22613.173070] kasan_report+0xe/0x20 [22613.173072] sysfs_kf_seq_show+0x117/0x230 [22613.173105] seq_read+0x199/0x6d0 [22613.173110] vfs_read+0xa5/0x1a0 [22613.173113] ksys_read+0x110/0x160 [22613.173115] ? kernel_write+0xb0/0xb0 [22613.173177] do_syscall_64+0x77/0x290 [22613.173238] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [22613.173241] RIP: 0033:0x7fc2c886ac61 [22613.173244] Code: fe ff ff 48 8d 3d c7 a0 09 00 48 83 ec 08 e8 46 03 02 00 66 0f 1f 44 00 00 8b 05 ca fb 2c 00 48 63 ff 85 c0 75 13 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 57 f3 c3 0f 1f 44 00 00 55 53 48 89 d5 48 89 [22613.173245] RSP: 002b:00007ffebe776d68 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [22613.173248] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007fc2c886ac61 [22613.173249] RDX: 0000000000020000 RSI: 00007fc2c8cca000 RDI: 0000000000000003 [22613.173250] RBP: 0000000000020000 R08: ffffffffffffffff R09: 0000000000000000 [22613.173251] R10: 000000000000038c R11: 0000000000000246 R12: 00007fc2c8cca000 [22613.173253] R13: 0000000000000003 R14: 00007fc2c8cca00f R15: 0000000000020000 [22613.173255] ================================================================== [22613.173256] Disabling lock debugging due to kernel taint [22613.173350] BUG: kernel NULL pointer dereference, address: 0000000000000000 [22613.178380] #PF: supervisor read access in kernel mode [22613.180959] #PF: error_code(0x0000) - not-present page [22613.183444] PGD 0 P4D 0 [22613.184867] Oops: 0000 [#1] SMP KASAN PTI [22613.186797] CPU: 1 PID: 6753 Comm: cat Tainted: G B 5.5.0-rc7-lp151.28.16-default+ #11 [22613.191253] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/29/2019 [22613.196706] RIP: 0010:sysfs_kf_seq_show+0x117/0x230 [22613.199097] Code: ff 48 8b 0b 48 8b 44 24 08 48 01 e9 eb a6 31 f6 48 89 cf ba 00 10 00 00 48 89 4c 24 10 e8 b1 e6 e9 ff 4c 89 ff e8 19 07 ea ff <49> 8b 07 48 85 c0 48 89 44 24 08 0f 84 91 00 00 00 49 8b 6d 00 48 [22613.208016] RSP: 0018:ffff8881d4f8fd78 EFLAGS: 00010246 [22613.210448] RAX: 0000000000000000 RBX: ffff8881eb99b180 RCX: ffffffff810d9ef6 [22613.213691] RDX: 0000000000000001 RSI: 0000000000000246 RDI: 0000000000000246 [22613.216893] RBP: 0000000000001000 R08: fffffbfff072ddcd R09: fffffbfff072ddcd [22613.220075] R10: 0000000000000001 R11: fffffbfff072ddcc R12: ffff8881de5c0200 [22613.223256] R13: ffff8881ed175500 R14: ffff8881eb99b198 R15: 0000000000000000 [22613.226290] FS: 00007fc2c8d3d500(0000) GS:ffff8881f2a80000(0000) knlGS:0000000000000000 [22613.229637] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [22613.231993] CR2: 0000000000000000 CR3: 00000001ec89a004 CR4: 00000000003606e0 [22613.234909] Call Trace: [22613.235931] seq_read+0x199/0x6d0 [22613.237259] vfs_read+0xa5/0x1a0 [22613.239229] ksys_read+0x110/0x160 [22613.240590] ? kernel_write+0xb0/0xb0 [22613.242040] do_syscall_64+0x77/0x290 [22613.243625] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [22613.245450] RIP: 0033:0x7fc2c886ac61 [22613.246706] Code: fe ff ff 48 8d 3d c7 a0 09 00 48 83 ec 08 e8 46 03 02 00 66 0f 1f 44 00 00 8b 05 ca fb 2c 00 48 63 ff 85 c0 75 13 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 57 f3 c3 0f 1f 44 00 00 55 53 48 89 d5 48 89 [22613.253296] RSP: 002b:00007ffebe776d68 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [22613.255835] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007fc2c886ac61 [22613.258472] RDX: 0000000000020000 RSI: 00007fc2c8cca000 RDI: 0000000000000003 [22613.260807] RBP: 0000000000020000 R08: ffffffffffffffff R09: 0000000000000000 [22613.263188] R10: 000000000000038c R11: 0000000000000246 R12: 00007fc2c8cca000 [22613.265598] R13: 0000000000000003 R14: 00007fc2c8cca00f R15: 0000000000020000 [22613.268729] Modules linked in: scsi_transport_iscsi af_packet iscsi_ibft iscsi_boot_sysfs vmw_vsock_vmci_transport vsock fuse bnep kvm_intel kvm irqbypass crc32_pclmul crc32c_intel ghash_clmulni_intel snd_ens1371 snd_ac97_codec ac97_bus bcache snd_pcm btusb btrtl btbcm btintel crc64 aesni_intel glue_helper crypto_simd vmw_balloon cryptd bluetooth snd_timer snd_rawmidi snd joydev pcspkr e1000 rfkill vmw_vmci soundcore ecdh_generic ecc gameport i2c_piix4 mptctl ac button hid_generic usbhid sr_mod cdrom ata_generic ehci_pci vmwgfx uhci_hcd drm_kms_helper syscopyarea serio_raw sysfillrect sysimgblt fb_sys_fops ttm ehci_hcd mptspi scsi_transport_spi mptscsih ata_piix mptbase ahci usbcore libahci drm sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua [22613.292429] CR2: 0000000000000000 [22613.293563] ---[ end trace a074b26a8508f378 ]--- [22613.295138] RIP: 0010:sysfs_kf_seq_show+0x117/0x230 [22613.296769] Code: ff 48 8b 0b 48 8b 44 24 08 48 01 e9 eb a6 31 f6 48 89 cf ba 00 10 00 00 48 89 4c 24 10 e8 b1 e6 e9 ff 4c 89 ff e8 19 07 ea ff <49> 8b 07 48 85 c0 48 89 44 24 08 0f 84 91 00 00 00 49 8b 6d 00 48 [22613.303553] RSP: 0018:ffff8881d4f8fd78 EFLAGS: 00010246 [22613.305280] RAX: 0000000000000000 RBX: ffff8881eb99b180 RCX: ffffffff810d9ef6 [22613.307924] RDX: 0000000000000001 RSI: 0000000000000246 RDI: 0000000000000246 [22613.310272] RBP: 0000000000001000 R08: fffffbfff072ddcd R09: fffffbfff072ddcd [22613.312685] R10: 0000000000000001 R11: fffffbfff072ddcc R12: ffff8881de5c0200 [22613.315076] R13: ffff8881ed175500 R14: ffff8881eb99b198 R15: 0000000000000000 [22613.318116] FS: 00007fc2c8d3d500(0000) GS:ffff8881f2a80000(0000) knlGS:0000000000000000 [22613.320743] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [22613.322628] CR2: 0000000000000000 CR3: 00000001ec89a004 CR4: 00000000003606e0 Here this patch fixes the following problem by explicity set all the 7 members to 0 in bch_cache_accounting_clear(). Reported-by: Сорокин Артем Сергеевич Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- drivers/md/bcache/stats.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/bcache/stats.c b/drivers/md/bcache/stats.c index ba1c93791d8d..503aafe188dc 100644 --- a/drivers/md/bcache/stats.c +++ b/drivers/md/bcache/stats.c @@ -109,9 +109,13 @@ int bch_cache_accounting_add_kobjs(struct cache_accounting *acc, void bch_cache_accounting_clear(struct cache_accounting *acc) { - memset(&acc->total.cache_hits, - 0, - sizeof(struct cache_stats)); + acc->total.cache_hits = 0; + acc->total.cache_misses = 0; + acc->total.cache_bypass_hits = 0; + acc->total.cache_bypass_misses = 0; + acc->total.cache_readaheads = 0; + acc->total.cache_miss_collisions = 0; + acc->total.sectors_bypassed = 0; } void bch_cache_accounting_destroy(struct cache_accounting *acc) -- cgit v1.2.3 From 7c02b0055f774ed9afb6e1c7724f33bf148ffdc0 Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 1 Feb 2020 22:42:32 +0800 Subject: bcache: explicity type cast in bset_bkey_last() In bset.h, macro bset_bkey_last() is defined as, bkey_idx((struct bkey *) (i)->d, (i)->keys) Parameter i can be variable type of data structure, the macro always works once the type of struct i has member 'd' and 'keys'. bset_bkey_last() is also used in macro csum_set() to calculate the checksum of a on-disk data structure. When csum_set() is used to calculate checksum of on-disk bcache super block, the parameter 'i' data type is struct cache_sb_disk. Inside struct cache_sb_disk (also in struct cache_sb) the member keys is __u16 type. But bkey_idx() expects unsigned int (a 32bit width), so there is problem when sending parameters via stack to call bkey_idx(). Sparse tool from Intel 0day kbuild system reports this incompatible problem. bkey_idx() is part of user space API, so the simplest fix is to cast the (i)->keys to unsigned int type in macro bset_bkey_last(). Reported-by: kbuild test robot Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- drivers/md/bcache/bset.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/md') diff --git a/drivers/md/bcache/bset.h b/drivers/md/bcache/bset.h index c71365e7c1fa..a50dcfda656f 100644 --- a/drivers/md/bcache/bset.h +++ b/drivers/md/bcache/bset.h @@ -397,7 +397,8 @@ void bch_btree_keys_stats(struct btree_keys *b, struct bset_stats *state); /* Bkey utility code */ -#define bset_bkey_last(i) bkey_idx((struct bkey *) (i)->d, (i)->keys) +#define bset_bkey_last(i) bkey_idx((struct bkey *) (i)->d, \ + (unsigned int)(i)->keys) static inline struct bkey *bset_bkey_idx(struct bset *i, unsigned int idx) { -- cgit v1.2.3 From 038ba8cc1bffc51250add4a9b9249d4331576d8f Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 1 Feb 2020 22:42:33 +0800 Subject: bcache: add readahead cache policy options via sysfs interface In year 2007 high performance SSD was still expensive, in order to save more space for real workload or meta data, the readahead I/Os for non-meta data was bypassed and not cached on SSD. In now days, SSD price drops a lot and people can find larger size SSD with more comfortable price. It is unncessary to alway bypass normal readahead I/Os to save SSD space for now. This patch adds options for readahead data cache policies via sysfs file /sys/block/bcache/readahead_cache_policy, the options are, - "all": cache all readahead data I/Os. - "meta-only": only cache meta data, and bypass other regular I/Os. If users want to make bcache continue to only cache readahead request for metadata and bypass regular data readahead, please set "meta-only" to this sysfs file. By default, bcache will back to cache all read- ahead requests now. Cc: stable@vger.kernel.org Signed-off-by: Coly Li Acked-by: Eric Wheeler Cc: Michael Lyle Signed-off-by: Jens Axboe --- drivers/md/bcache/bcache.h | 3 +++ drivers/md/bcache/request.c | 17 ++++++++++++----- drivers/md/bcache/sysfs.c | 22 ++++++++++++++++++++++ 3 files changed, 37 insertions(+), 5 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h index adf26a21fcd1..74a9849ea164 100644 --- a/drivers/md/bcache/bcache.h +++ b/drivers/md/bcache/bcache.h @@ -330,6 +330,9 @@ struct cached_dev { */ atomic_t has_dirty; +#define BCH_CACHE_READA_ALL 0 +#define BCH_CACHE_READA_META_ONLY 1 + unsigned int cache_readahead_policy; struct bch_ratelimit writeback_rate; struct delayed_work writeback_rate_update; diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c index 73478a91a342..820d8402a1dc 100644 --- a/drivers/md/bcache/request.c +++ b/drivers/md/bcache/request.c @@ -379,13 +379,20 @@ static bool check_should_bypass(struct cached_dev *dc, struct bio *bio) goto skip; /* - * Flag for bypass if the IO is for read-ahead or background, - * unless the read-ahead request is for metadata + * If the bio is for read-ahead or background IO, bypass it or + * not depends on the following situations, + * - If the IO is for meta data, always cache it and no bypass + * - If the IO is not meta data, check dc->cache_reada_policy, + * BCH_CACHE_READA_ALL: cache it and not bypass + * BCH_CACHE_READA_META_ONLY: not cache it and bypass + * That is, read-ahead request for metadata always get cached * (eg, for gfs2 or xfs). */ - if (bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND) && - !(bio->bi_opf & (REQ_META|REQ_PRIO))) - goto skip; + if ((bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND))) { + if (!(bio->bi_opf & (REQ_META|REQ_PRIO)) && + (dc->cache_readahead_policy != BCH_CACHE_READA_ALL)) + goto skip; + } if (bio->bi_iter.bi_sector & (c->sb.block_size - 1) || bio_sectors(bio) & (c->sb.block_size - 1)) { diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c index 733e2ddf3c78..3470fae4eabc 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -27,6 +27,12 @@ static const char * const bch_cache_modes[] = { NULL }; +static const char * const bch_reada_cache_policies[] = { + "all", + "meta-only", + NULL +}; + /* Default is 0 ("auto") */ static const char * const bch_stop_on_failure_modes[] = { "auto", @@ -100,6 +106,7 @@ rw_attribute(congested_write_threshold_us); rw_attribute(sequential_cutoff); rw_attribute(data_csum); rw_attribute(cache_mode); +rw_attribute(readahead_cache_policy); rw_attribute(stop_when_cache_set_failed); rw_attribute(writeback_metadata); rw_attribute(writeback_running); @@ -168,6 +175,11 @@ SHOW(__bch_cached_dev) bch_cache_modes, BDEV_CACHE_MODE(&dc->sb)); + if (attr == &sysfs_readahead_cache_policy) + return bch_snprint_string_list(buf, PAGE_SIZE, + bch_reada_cache_policies, + dc->cache_readahead_policy); + if (attr == &sysfs_stop_when_cache_set_failed) return bch_snprint_string_list(buf, PAGE_SIZE, bch_stop_on_failure_modes, @@ -353,6 +365,15 @@ STORE(__cached_dev) } } + if (attr == &sysfs_readahead_cache_policy) { + v = __sysfs_match_string(bch_reada_cache_policies, -1, buf); + if (v < 0) + return v; + + if ((unsigned int) v != dc->cache_readahead_policy) + dc->cache_readahead_policy = v; + } + if (attr == &sysfs_stop_when_cache_set_failed) { v = __sysfs_match_string(bch_stop_on_failure_modes, -1, buf); if (v < 0) @@ -467,6 +488,7 @@ static struct attribute *bch_cached_dev_files[] = { &sysfs_data_csum, #endif &sysfs_cache_mode, + &sysfs_readahead_cache_policy, &sysfs_stop_when_cache_set_failed, &sysfs_writeback_metadata, &sysfs_writeback_running, -- cgit v1.2.3 From d1c3cc34f5a78b38d2b809b289d912c3560545df Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 1 Feb 2020 22:42:34 +0800 Subject: bcache: fix incorrect data type usage in btree_flush_write() Dan Carpenter points out that from commit 2aa8c529387c ("bcache: avoid unnecessary btree nodes flushing in btree_flush_write()"), there is a incorrect data type usage which leads to the following static checker warning: drivers/md/bcache/journal.c:444 btree_flush_write() warn: 'ref_nr' unsigned <= 0 drivers/md/bcache/journal.c 422 static void btree_flush_write(struct cache_set *c) 423 { 424 struct btree *b, *t, *btree_nodes[BTREE_FLUSH_NR]; 425 unsigned int i, nr, ref_nr; ^^^^^^ 426 atomic_t *fifo_front_p, *now_fifo_front_p; 427 size_t mask; 428 429 if (c->journal.btree_flushing) 430 return; 431 432 spin_lock(&c->journal.flush_write_lock); 433 if (c->journal.btree_flushing) { 434 spin_unlock(&c->journal.flush_write_lock); 435 return; 436 } 437 c->journal.btree_flushing = true; 438 spin_unlock(&c->journal.flush_write_lock); 439 440 /* get the oldest journal entry and check its refcount */ 441 spin_lock(&c->journal.lock); 442 fifo_front_p = &fifo_front(&c->journal.pin); 443 ref_nr = atomic_read(fifo_front_p); 444 if (ref_nr <= 0) { ^^^^^^^^^^^ Unsigned can't be less than zero. 445 /* 446 * do nothing if no btree node references 447 * the oldest journal entry 448 */ 449 spin_unlock(&c->journal.lock); 450 goto out; 451 } 452 spin_unlock(&c->journal.lock); As the warning information indicates, local varaible ref_nr in unsigned int type is wrong, which does not matche atomic_read() and the "<= 0" checking. This patch fixes the above error by defining local variable ref_nr as int type. Fixes: 2aa8c529387c ("bcache: avoid unnecessary btree nodes flushing in btree_flush_write()") Reported-by: Dan Carpenter Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- drivers/md/bcache/journal.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/md') diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c index 33ddc5269e8d..6730820780b0 100644 --- a/drivers/md/bcache/journal.c +++ b/drivers/md/bcache/journal.c @@ -422,7 +422,8 @@ err: static void btree_flush_write(struct cache_set *c) { struct btree *b, *t, *btree_nodes[BTREE_FLUSH_NR]; - unsigned int i, nr, ref_nr; + unsigned int i, nr; + int ref_nr; atomic_t *fifo_front_p, *now_fifo_front_p; size_t mask; -- cgit v1.2.3 From 49d08d596e85f39ded48e85df362827cbab1f5ae Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 1 Feb 2020 22:42:35 +0800 Subject: bcache: check return value of prio_read() Now if prio_read() failed during starting a cache set, we can print out error message in run_cache_set() and handle the failure properly. Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- drivers/md/bcache/super.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index 3dea1d5acd5c..2749daf09724 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -609,12 +609,13 @@ int bch_prio_write(struct cache *ca, bool wait) return 0; } -static void prio_read(struct cache *ca, uint64_t bucket) +static int prio_read(struct cache *ca, uint64_t bucket) { struct prio_set *p = ca->disk_buckets; struct bucket_disk *d = p->data + prios_per_bucket(ca), *end = d; struct bucket *b; unsigned int bucket_nr = 0; + int ret = -EIO; for (b = ca->buckets; b < ca->buckets + ca->sb.nbuckets; @@ -627,11 +628,15 @@ static void prio_read(struct cache *ca, uint64_t bucket) prio_io(ca, bucket, REQ_OP_READ, 0); if (p->csum != - bch_crc64(&p->magic, bucket_bytes(ca) - 8)) + bch_crc64(&p->magic, bucket_bytes(ca) - 8)) { pr_warn("bad csum reading priorities"); + goto out; + } - if (p->magic != pset_magic(&ca->sb)) + if (p->magic != pset_magic(&ca->sb)) { pr_warn("bad magic reading priorities"); + goto out; + } bucket = p->next_bucket; d = p->data; @@ -640,6 +645,10 @@ static void prio_read(struct cache *ca, uint64_t bucket) b->prio = le16_to_cpu(d->prio); b->gen = b->last_gc = d->gen; } + + ret = 0; +out: + return ret; } /* Bcache device */ @@ -1873,8 +1882,10 @@ static int run_cache_set(struct cache_set *c) j = &list_entry(journal.prev, struct journal_replay, list)->j; err = "IO error reading priorities"; - for_each_cache(ca, c, i) - prio_read(ca, j->prio_bucket[ca->sb.nr_this_dev]); + for_each_cache(ca, c, i) { + if (prio_read(ca, j->prio_bucket[ca->sb.nr_this_dev])) + goto err; + } /* * If prio_read() fails it'll call cache_set_error and we'll -- cgit v1.2.3