kernel.git/drivers/md/bcache/super.c, branch linux-5.4.y

bcache: revert replacing IS_ERR_OR_NULL with IS_ERR again

2024-12-14T18:44:49Z

commit b2e382ae12a63560fca35050498e19e760adf8c0 upstream. Commit 028ddcac477b ("bcache: Remove unnecessary NULL point check in node allocations") leads a NULL pointer deference in cache_set_flush(). 1721 if (!IS_ERR_OR_NULL(c->root)) 1722 list_add(&c->root->list, &c->btree_cache); >From the above code in cache_set_flush(), if previous registration code fails before allocating c->root, it is possible c->root is NULL as what it is initialized. __bch_btree_node_alloc() never returns NULL but c->root is possible to be NULL at above line 1721. This patch replaces IS_ERR() by IS_ERR_OR_NULL() to fix this. Fixes: 028ddcac477b ("bcache: Remove unnecessary NULL point check in node allocations") Signed-off-by: Liequan Che Cc: stable@vger.kernel.org Cc: Zheng Wang Reviewed-by: Mingzhe Zou Signed-off-by: Coly Li Link: https://lore.kernel.org/r/20241202115638.28957-1-colyli@suse.de Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

bcache: avoid NULL checking to c->root in run_cache_set()

2023-12-20T14:41:20Z

[ Upstream commit 3eba5e0b2422aec3c9e79822029599961fdcab97 ] In run_cache_set() after c->root returned from bch_btree_node_get(), it is checked by IS_ERR_OR_NULL(). Indeed it is unncessary to check NULL because bch_btree_node_get() will not return NULL pointer to caller. This patch replaces IS_ERR_OR_NULL() by IS_ERR() for the above reason. Signed-off-by: Coly Li Link: https://lore.kernel.org/r/20231120052503.6122-11-colyli@suse.de Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

bcache: avoid oversize memory allocation by small stripe_size

2023-12-20T14:41:20Z

[ Upstream commit baf8fb7e0e5ec54ea0839f0c534f2cdcd79bea9c ] Arraies bcache->stripe_sectors_dirty and bcache->full_dirty_stripes are used for dirty data writeback, their sizes are decided by backing device capacity and stripe size. Larger backing device capacity or smaller stripe size make these two arraies occupies more dynamic memory space. Currently bcache->stripe_size is directly inherited from queue->limits.io_opt of underlying storage device. For normal hard drives, its limits.io_opt is 0, and bcache sets the corresponding stripe_size to 1TB (1<<31 sectors), it works fine 10+ years. But for devices do declare value for queue->limits.io_opt, small stripe_size (comparing to 1TB) becomes an issue for oversize memory allocations of bcache->stripe_sectors_dirty and bcache->full_dirty_stripes, while the capacity of hard drives gets much larger in recent decade. For example a raid5 array assembled by three 20TB hardrives, the raid device capacity is 40TB with typical 512KB limits.io_opt. After the math calculation in bcache code, these two arraies will occupy 400MB dynamic memory. Even worse Andrea Tomassetti reports that a 4KB limits.io_opt is declared on a new 2TB hard drive, then these two arraies request 2GB and 512MB dynamic memory from kzalloc(). The result is that bcache device always fails to initialize on his system. To avoid the oversize memory allocation, bcache->stripe_size should not directly inherited by queue->limits.io_opt from the underlying device. This patch defines BCH_MIN_STRIPE_SZ (4MB) as minimal bcache stripe size and set bcache device's stripe size against the declared limits.io_opt value from the underlying storage device, - If the declared limits.io_opt > BCH_MIN_STRIPE_SZ, bcache device will set its stripe size directly by this limits.io_opt value. - If the declared limits.io_opt < BCH_MIN_STRIPE_SZ, bcache device will set its stripe size by a value multiplying limits.io_opt and euqal or large than BCH_MIN_STRIPE_SZ. Then the minimal stripe size of a bcache device will always be >= 4MB. For a 40TB raid5 device with 512KB limits.io_opt, memory occupied by bcache->stripe_sectors_dirty and bcache->full_dirty_stripes will be 50MB in total. For a 2TB hard drive with 4KB limits.io_opt, memory occupied by these two arraies will be 2.5MB in total. Such mount of memory allocated for bcache->stripe_sectors_dirty and bcache->full_dirty_stripes is reasonable for most of storage devices. Reported-by: Andrea Tomassetti Signed-off-by: Coly Li Reviewed-by: Eric Wheeler Link: https://lore.kernel.org/r/20231120052503.6122-2-colyli@suse.de Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

bcache: remove 'int n' from parameter list of bch_bucket_alloc_set()

2023-08-11T09:53:44Z

[ Upstream commit 17e4aed8309ff28670271546c2c3263eb12f5eb6 ] The parameter 'int n' from bch_bucket_alloc_set() is not cleared defined. From the code comments n is the number of buckets to alloc, but from the code itself 'n' is the maximum cache to iterate. Indeed all the locations where bch_bucket_alloc_set() is called, 'n' is alwasy 1. This patch removes the confused and unnecessary 'int n' from parameter list of bch_bucket_alloc_set(), and explicitly allocates only 1 bucket for its caller. Signed-off-by: Coly Li Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe Stable-dep-of: 80fca8a10b60 ("bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent") Signed-off-by: Sasha Levin

bcache: Remove unnecessary NULL point check in node allocations

2023-07-27T06:37:25Z

commit 028ddcac477b691dd9205c92f991cc15259d033e upstream. Due to the previous fix of __bch_btree_node_alloc, the return value will never be a NULL pointer. So IS_ERR is enough to handle the failure situation. Fix it by replacing IS_ERR_OR_NULL check by an IS_ERR check. Fixes: cafe56359144 ("bcache: A block layer cache") Cc: stable@vger.kernel.org Signed-off-by: Zheng Wang Signed-off-by: Coly Li Link: https://lore.kernel.org/r/20230615121223.22502-5-colyli@suse.de Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

bcache: add proper error unwinding in bcache_device_init

2021-09-15T07:47:27Z

[ Upstream commit 224b0683228c5f332f9cee615d85e75e9a347170 ] Except for the IDA none of the allocations in bcache_device_init is unwound on error, fix that. Signed-off-by: Christoph Hellwig Acked-by: Coly Li Link: https://lore.kernel.org/r/20210809064028.1198327-7-hch@lst.de Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

bcache: Move journal work to new flush wq

2021-03-04T09:26:43Z

commit afe78ab46f638ecdf80a35b122ffc92c20d9ae5d upstream. This is potentially long running and not latency sensitive, let's get it out of the way of other latency sensitive events. As observed in the previous commit, the `system_wq` comes easily congested by bcache, and this fixes a few more stalls I was observing every once in a while. Let's not make this `WQ_MEM_RECLAIM` as it showed to reduce performance of boot and file system operations in my tests. Also, without `WQ_MEM_RECLAIM`, I no longer see desktop stalls. This matches the previous behavior as `system_wq` also does no memory reclaim: > // workqueue.c: > system_wq = alloc_workqueue("events", 0, 0); Cc: Coly Li Cc: stable@vger.kernel.org # 5.4+ Signed-off-by: Kai Krakow Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

Revert "bcache: Kill btree_io_wq"

2021-03-04T09:26:42Z

commit 9f233ffe02e5cef611100cd8c5bcf4de26ca7bef upstream. This reverts commit 56b30770b27d54d68ad51eccc6d888282b568cee. With the btree using the `system_wq`, I seem to see a lot more desktop latency than I should. After some more investigation, it looks like the original assumption of 56b3077 no longer is true, and bcache has a very high potential of congesting the `system_wq`. In turn, this introduces laggy desktop performance, IO stalls (at least with btrfs), and input events may be delayed. So let's revert this. It's important to note that the semantics of using `system_wq` previously mean that `btree_io_wq` should be created before and destroyed after other bcache wqs to keep the same assumptions. Cc: Coly Li Cc: stable@vger.kernel.org # 5.4+ Signed-off-by: Kai Krakow Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

bcache: fix a lost wake-up problem caused by mca_cannibalize_lock

2020-10-01T11:17:18Z

[ Upstream commit 34cf78bf34d48dddddfeeadb44f9841d7864997a ] This patch fix a lost wake-up problem caused by the race between mca_cannibalize_lock and bch_cannibalize_unlock. Consider two processes, A and B. Process A is executing mca_cannibalize_lock, while process B takes c->btree_cache_alloc_lock and is executing bch_cannibalize_unlock. The problem happens that after process A executes cmpxchg and will execute prepare_to_wait. In this timeslice process B executes wake_up, but after that process A executes prepare_to_wait and set the state to TASK_INTERRUPTIBLE. Then process A goes to sleep but no one will wake up it. This problem may cause bcache device to dead. Signed-off-by: Guoju Fang Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

bcache: avoid nr_stripes overflow in bcache_device_init()

2020-08-26T08:40:48Z

[ Upstream commit 65f0f017e7be8c70330372df23bcb2a407ecf02d ] For some block devices which large capacity (e.g. 8TB) but small io_opt size (e.g. 8 sectors), in bcache_device_init() the stripes number calcu- lated by, DIV_ROUND_UP_ULL(sectors, d->stripe_size); might be overflow to the unsigned int bcache_device->nr_stripes. This patch uses the uint64_t variable to store DIV_ROUND_UP_ULL() and after the value is checked to be available in unsigned int range, sets it to bache_device->nr_stripes. Then the overflow is avoided. Reported-and-tested-by: Ken Raeburn Signed-off-by: Coly Li Cc: stable@vger.kernel.org Link: https://bugzilla.redhat.com/show_bug.cgi?id=1783075 Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin