- 30 Apr, 2019 12 commits
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Christoph Hellwig authored
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
Various block layer files do not have any licensing information at all. Add SPDX tags for the default kernel GPLv2 license to those. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
This file has no copyright notice, but was added as part of a commit adding another file using the default kernel GPLv2 license. Add a matching SPDX tag. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
The file already has the correct SPDX header. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
All these files have some form of the usual GPLv2 or later boilerplate. Switch them to use SPDX tags instead. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
All these files have some form of the usual GPLv2 boilerplate. Switch them to use SPDX tags instead. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
Share the bi_size update by moving the done label up, and duplicate the bv_len update in the two callers to get rid of the bvec_merge label. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
We are never called with file system pages by defintions for the passthrough interface, and we also never undo any addition later these days. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
The same page optimization is a rather odd corner case, which is not used outside bio.c and which really should not be used outside of bio.c either - we have better highlevel helpers like the rq/bio mapping helpers. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
We only have two callers that need the integer loop iterator, and they can easily maintain it themselves. Suggested-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Acked-by: David Sterba <dsterba@suse.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Acked-by: Coly Li <colyli@suse.de> Reviewed-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Christoph Hellwig authored
Use a variable containing the buffer address instead of the to be removed integer iterator from bio_for_each_segment_all. Suggested-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Hannes Reinecke <hare@suse.com> Acked-by: Coly Li <colyli@suse.de> Reviewed-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
Commit 95f18c9d ("bcache: avoid potential memleak of list of journal_replay(s) in the CACHE_SYNC branch of run_cache_set") forgets to remove the original define of LIST_HEAD(journal), which makes the change no take effect. This patch removes redundant variable LIST_HEAD(journal) from run_cache_set(), to make Shenghui's fix working. Fixes: 95f18c9d ("bcache: avoid potential memleak of list of journal_replay(s) in the CACHE_SYNC branch of run_cache_set") Reported-by: Juha Aatrokoski <juha.aatrokoski@aalto.fi> Cc: Shenghui Wang <shhuiw@foxmail.com> Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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- 26 Apr, 2019 1 commit
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git://git.infradead.org/nvmeJens Axboe authored
Pull NVMe changes from Christoph. * 'nvme-5.2' of git://git.infradead.org/nvme: nvme: set 0 capacity if namespace block size exceeds PAGE_SIZE nvme-rdma: fix typo in struct comment nvme-loop: kill timeout handler nvme-tcp: rename function to have nvme_tcp prefix nvme-rdma: fix a NULL deref when an admin connect times out nvme-tcp: fix a NULL deref when an admin connect times out nvmet-tcp: don't fail maxr2t greater than 1 nvmet-file: clamp-down file namespace lba_shift nvmet: include <linux/scatterlist.h> nvmet: return a specified error it subsys_alloc fails nvmet: rename nvme_completion instances from rsp to cqe nvmet-rdma: remove p2p_client initialization from fast-path
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- 25 Apr, 2019 13 commits
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Christoph Hellwig authored
The trim support in mtip32xx has been "temporarily" disabled for 6 years, which is 3/4 of the time the driver even exists in the tree. Remove it as it obviously is dead code now. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Sagi Grimberg authored
If our target exposed a namespace with a block size that is greater than PAGE_SIZE, set 0 capacity on the namespace as we do not support it. This issue encountered when the nvmet namespace was backed by a tempfile. Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Minwoo Im authored
struct nvme_rdma_cm_rej has two different attributes: recfmt and sts. And sts will have value what this comment wanted to show. Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Ming Lei authored
Firstly it doesn't make sense to handle timeout for loop: 1) for admin queue, the request is always completed in code path of queuing IO. 2) for normal IO request, the timeout on these IOs have been handled by underlying queue already. Secondly nvme-loop's timeout handler is simply broken, and easy to cause issue: 1) no any sync/protection between timeout and normal completion, and now it is driver's responsibility to deal with that; 2) bad reset implementation, blk_mq_update_nr_hw_queues() is called after all NSs's queue is stopped(quiesced), and easy to trigger deadlock. So kill the timeout handler. Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewd-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Sagi Grimberg authored
usually nvme_ prefix is for core functions. While we're cleaning up, remove redundant empty lines Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Minwoo Im <minwoo.im@samsung.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Sagi Grimberg authored
If we timeout the admin startup sequence we might not yet have an I/O tagset allocated which causes the teardown sequence to crash. Make nvme_tcp_teardown_io_queues safe by not iterating inflight tags if the tagset wasn't allocated. Fixes: 4c174e63 ("nvme-rdma: fix timeout handler") Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Sagi Grimberg authored
If we timeout the admin startup sequence we might not yet have an I/O tagset allocated which causes the teardown sequence to crash. Make nvme_tcp_teardown_io_queues safe by not iterating inflight tags if the tagset wasn't allocated. Fixes: 39d57757 ("nvme-tcp: fix timeout handler") Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Sagi Grimberg authored
The host may support it, but nothing prevents us from sending a single r2t at a time like we do anyways. Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Sagi Grimberg authored
When the backing file is a tempfile for example, the inode i_blkbits can be 1M in size which causes problems for hosts to support as the disk block size. Instead, expose the minimum between i_blkbits and 12 (4K sector size). Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: - Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Enrico Weigelt, metux IT consult authored
Build breaks: drivers/nvme/target/core.c: In function 'nvmet_req_alloc_sgl': drivers/nvme/target/core.c:939:12: error: implicit declaration of \ function 'sgl_alloc'; did you mean 'bio_alloc'? \ [-Werror=implicit-function-declaration] req->sg = sgl_alloc(req->transfer_len, GFP_KERNEL, &req->sg_cnt); ^~~~~~~~~ bio_alloc drivers/nvme/target/core.c:939:10: warning: assignment makes pointer \ from integer without a cast [-Wint-conversion] req->sg = sgl_alloc(req->transfer_len, GFP_KERNEL, &req->sg_cnt); ^ drivers/nvme/target/core.c: In function 'nvmet_req_free_sgl': drivers/nvme/target/core.c:952:3: error: implicit declaration of \ function 'sgl_free'; did you mean 'ida_free'? [-Werror=implicit-function-declaration] sgl_free(req->sg); ^~~~~~~~ ida_free Cause: 1. missing include to <linux/scatterlist.h> 2. SGL_ALLOC needs to be enabled Therefore adding the missing include, as well as Kconfig dependency. Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Minwoo Im <minwoo.im@samsung.com> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Minwoo Im authored
nvmet_subsys_alloc() returns its pointer or NULL if it fails. We can see three different steps in this function: 1. memory allocation 2. argument check 3. memory allocation for string But now the callers of this function do not seem to handle case 2 by returning -ENOMEM only even if it fails with an invalid parameter. This patch specifies error codes so that caller can pass it to its own caller. Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>. Signed-off-by: Christoph Hellwig <hch@lst.de>
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Max Gurtovoy authored
Use NVMe namings for improving code readability. Signed-off-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by : Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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Max Gurtovoy authored
Initialize it during command allocation. Cc: Logan Gunthorpe <logang@deltatee.com> Cc: Stephen Bates <sbates@raithlin.com> Signed-off-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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- 24 Apr, 2019 14 commits
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Shenghui Wang authored
bcache: avoid potential memleak of list of journal_replay(s) in the CACHE_SYNC branch of run_cache_set In the CACHE_SYNC branch of run_cache_set(), LIST_HEAD(journal) is used to collect journal_replay(s) and filled by bch_journal_read(). If all goes well, bch_journal_replay() will release the list of jounal_replay(s) at the end of the branch. If something goes wrong, code flow will jump to the label "err:" and leave the list unreleased. This patch will release the list of journal_replay(s) in the case of error detected. v1 -> v2: * Move the release code to the location after label 'err:' to simply the change. Signed-off-by: Shenghui Wang <shhuiw@foxmail.com> Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Shenghui Wang authored
Elements of keylist should be accessed before the list is freed. Move bch_keylist_free() calling after the while loop to avoid wrong content accessed. Signed-off-by: Shenghui Wang <shhuiw@foxmail.com> Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Tang Junhui authored
journal replay failed with messages: Sep 10 19:10:43 ceph kernel: bcache: error on bb379a64-e44e-4812-b91d-a5599871a3b1: bcache: journal entries 2057493-2057567 missing! (replaying 2057493-20766016), disabling caching The reason is in journal_reclaim(), when discard is enabled, we send discard command and reclaim those journal buckets whose seq is old than the last_seq_now, but before we write a journal with last_seq_now, the machine is restarted, so the journal with the last_seq_now is not written to the journal bucket, and the last_seq_wrote in the newest journal is old than last_seq_now which we expect to be, so when we doing replay, journals from last_seq_wrote to last_seq_now are missing. It's hard to write a journal immediately after journal_reclaim(), and it harmless if those missed journal are caused by discarding since those journals are already wrote to btree node. So, if miss seqs are started from the beginning journal, we treat it as normal, and only print a message to show the miss journal, and point out it maybe caused by discarding. Patch v2 add a judgement condition to ignore the missed journal only when discard enabled as Coly suggested. (Coly Li: rebase the patch with other changes in bch_journal_replay()) Signed-off-by: Tang Junhui <tang.junhui.linux@gmail.com> Tested-by: Dennis Schridde <devurandom@gmx.net> Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
This patch tries to release mutex bch_register_lock early, to give chance to stop cache set and bcache device early. This patch also expends time out of stopping all bcache device from 2 seconds to 10 seconds, because stopping writeback rate update worker may delay for 5 seconds, 2 seconds is not enough. After this patch applied, stopping bcache devices during system reboot or shutdown is very hard to be observed any more. Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
Add code comments to explain which call back function might be called for the closure_queue(). This is an effort to make code to be more understandable for readers. Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
Add comments to explain why in register_bcache() blkdev_put() won't be called in two location. Add comments to explain why blkdev_put() must be called in register_cache() when cache_alloc() failed. Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
This patch adds return value to register_bdev(). Then if failure happens inside register_bdev(), its caller register_bcache() may detect and handle the failure more properly. Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
When failure happens inside bch_journal_replay(), calling cache_set_err_on() and handling the failure in async way is not a good idea. Because after bch_journal_replay() returns, registering code will continue to execute following steps, and unregistering code triggered by cache_set_err_on() is running in same time. First it is unnecessary to handle failure and unregister cache set in an async way, second there might be potential race condition to run register and unregister code for same cache set. So in this patch, if failure happens in bch_journal_replay(), we don't call cache_set_err_on(), and just print out the same error message to kernel message buffer, then return -EIO immediately caller. Then caller can detect such failure and handle it in synchrnozied way. Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
Bcache has several routines to release resources in implicit way, they are called when the associated kobj released. This patch adds code comments to notice when and which release callback will be called, - When dc->disk.kobj released: void bch_cached_dev_release(struct kobject *kobj) - When d->kobj released: void bch_flash_dev_release(struct kobject *kobj) - When c->kobj released: void bch_cache_set_release(struct kobject *kobj) - When ca->kobj released void bch_cache_release(struct kobject *kobj) Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
Currently run_cache_set() has no return value, if there is failure in bch_journal_replay(), the caller of run_cache_set() has no idea about such failure and just continue to execute following code after run_cache_set(). The internal failure is triggered inside bch_journal_replay() and being handled in async way. This behavior is inefficient, while failure handling inside bch_journal_replay(), cache register code is still running to start the cache set. Registering and unregistering code running as same time may introduce some rare race condition, and make the code to be more hard to be understood. This patch adds return value to run_cache_set(), and returns -EIO if bch_journal_rreplay() fails. Then caller of run_cache_set() may detect such failure and stop registering code flow immedidately inside register_cache_set(). If journal replay fails, run_cache_set() can report error immediately to register_cache_set(). This patch makes the failure handling for bch_journal_replay() be in synchronized way, easier to understand and debug, and avoid poetential race condition for register-and-unregister in same time. Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
In journal_reclaim() ja->cur_idx of each cache will be update to reclaim available journal buckets. Variable 'int n' is used to count how many cache is successfully reclaimed, then n is set to c->journal.key by SET_KEY_PTRS(). Later in journal_write_unlocked(), a for_each_cache() loop will write the jset data onto each cache. The problem is, if all jouranl buckets on each cache is full, the following code in journal_reclaim(), 529 for_each_cache(ca, c, iter) { 530 struct journal_device *ja = &ca->journal; 531 unsigned int next = (ja->cur_idx + 1) % ca->sb.njournal_buckets; 532 533 /* No space available on this device */ 534 if (next == ja->discard_idx) 535 continue; 536 537 ja->cur_idx = next; 538 k->ptr[n++] = MAKE_PTR(0, 539 bucket_to_sector(c, ca->sb.d[ja->cur_idx]), 540 ca->sb.nr_this_dev); 541 } 542 543 bkey_init(k); 544 SET_KEY_PTRS(k, n); If there is no available bucket to reclaim, the if() condition at line 534 will always true, and n remains 0. Then at line 544, SET_KEY_PTRS() will set KEY_PTRS field of c->journal.key to 0. Setting KEY_PTRS field of c->journal.key to 0 is wrong. Because in journal_write_unlocked() the journal data is written in following loop, 649 for (i = 0; i < KEY_PTRS(k); i++) { 650-671 submit journal data to cache device 672 } If KEY_PTRS field is set to 0 in jouranl_reclaim(), the journal data won't be written to cache device here. If system crahed or rebooted before bkeys of the lost journal entries written into btree nodes, data corruption will be reported during bcache reload after rebooting the system. Indeed there is only one cache in a cache set, there is no need to set KEY_PTRS field in journal_reclaim() at all. But in order to keep the for_each_cache() logic consistent for now, this patch fixes the above problem by not setting 0 KEY_PTRS of journal key, if there is no bucket available to reclaim. Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Coly Li authored
'int ret' is defined as a local variable inside macro read_bucket(). Since this macro is called multiple times, and following patches will use a 'int ret' variable in bch_journal_read(), this patch moves definition of 'int ret' from macro read_bucket() to range of function bch_journal_read(). Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Liang Chen authored
There is a race between cache device register and cache set unregister. For an already registered cache device, register_bcache will call bch_is_open to iterate through all cachesets and check every cache there. The race occurs if cache_set_free executes at the same time and clears the caches right before ca is dereferenced in bch_is_open_cache. To close the race, let's make sure the clean up work is protected by the bch_register_lock as well. This issue can be reproduced as follows, while true; do echo /dev/XXX> /sys/fs/bcache/register ; done& while true; do echo 1> /sys/block/XXX/bcache/set/unregister ; done & and results in the following oops, [ +0.000053] BUG: unable to handle kernel NULL pointer dereference at 0000000000000998 [ +0.000457] #PF error: [normal kernel read fault] [ +0.000464] PGD 800000003ca9d067 P4D 800000003ca9d067 PUD 3ca9c067 PMD 0 [ +0.000388] Oops: 0000 [#1] SMP PTI [ +0.000269] CPU: 1 PID: 3266 Comm: bash Not tainted 5.0.0+ #6 [ +0.000346] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 04/01/2014 [ +0.000472] RIP: 0010:register_bcache+0x1829/0x1990 [bcache] [ +0.000344] Code: b0 48 83 e8 50 48 81 fa e0 e1 10 c0 0f 84 a9 00 00 00 48 89 c6 48 89 ca 0f b7 ba 54 04 00 00 4c 8b 82 60 0c 00 00 85 ff 74 2f <49> 3b a8 98 09 00 00 74 4e 44 8d 47 ff 31 ff 49 c1 e0 03 eb 0d [ +0.000839] RSP: 0018:ffff92ee804cbd88 EFLAGS: 00010202 [ +0.000328] RAX: ffffffffc010e190 RBX: ffff918b5c6b5000 RCX: ffff918b7d8e0000 [ +0.000399] RDX: ffff918b7d8e0000 RSI: ffffffffc010e190 RDI: 0000000000000001 [ +0.000398] RBP: ffff918b7d318340 R08: 0000000000000000 R09: ffffffffb9bd2d7a [ +0.000385] R10: ffff918b7eb253c0 R11: ffffb95980f51200 R12: ffffffffc010e1a0 [ +0.000411] R13: fffffffffffffff2 R14: 000000000000000b R15: ffff918b7e232620 [ +0.000384] FS: 00007f955bec2740(0000) GS:ffff918b7eb00000(0000) knlGS:0000000000000000 [ +0.000420] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ +0.000801] CR2: 0000000000000998 CR3: 000000003cad6000 CR4: 00000000001406e0 [ +0.000837] Call Trace: [ +0.000682] ? _cond_resched+0x10/0x20 [ +0.000691] ? __kmalloc+0x131/0x1b0 [ +0.000710] kernfs_fop_write+0xfa/0x170 [ +0.000733] __vfs_write+0x2e/0x190 [ +0.000688] ? inode_security+0x10/0x30 [ +0.000698] ? selinux_file_permission+0xd2/0x120 [ +0.000752] ? security_file_permission+0x2b/0x100 [ +0.000753] vfs_write+0xa8/0x1a0 [ +0.000676] ksys_write+0x4d/0xb0 [ +0.000699] do_syscall_64+0x3a/0xf0 [ +0.000692] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Liang Chen <liangchen.linux@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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George Spelvin authored
There are a few nits in this function. They could in theory all be separate patches, but that's probably taking small commits too far. 1) I added a brief comment saying what it does. 2) I like to declare pointer parameters "const" where possible for documentation reasons. 3) It uses bitmap_weight(&rand, BITS_PER_LONG) to compute the Hamming weight of a 32-bit random number (giving a random integer with mean 16 and variance 8). Passing by reference in a 64-bit variable is silly; just use hweight32(). 4) Its helper function fract_exp_two is unnecessarily tangled. Gcc can optimize the multiply by (1 << x) to a shift, but it can be written in a much more straightforward way at the cost of one more bit of internal precision. Some analysis reveals that this bit is always available. This shrinks the object code for fract_exp_two(x, 6) from 23 bytes: 0000000000000000 <foo1>: 0: 89 f9 mov %edi,%ecx 2: c1 e9 06 shr $0x6,%ecx 5: b8 01 00 00 00 mov $0x1,%eax a: d3 e0 shl %cl,%eax c: 83 e7 3f and $0x3f,%edi f: d3 e7 shl %cl,%edi 11: c1 ef 06 shr $0x6,%edi 14: 01 f8 add %edi,%eax 16: c3 retq To 19: 0000000000000017 <foo2>: 17: 89 f8 mov %edi,%eax 19: 83 e0 3f and $0x3f,%eax 1c: 83 c0 40 add $0x40,%eax 1f: 89 f9 mov %edi,%ecx 21: c1 e9 06 shr $0x6,%ecx 24: d3 e0 shl %cl,%eax 26: c1 e8 06 shr $0x6,%eax 29: c3 retq (Verified with 0 <= frac_bits <= 8, 0 <= x < 16<<frac_bits; both versions produce the same output.) 5) And finally, the call to bch_get_congested() in check_should_bypass() is separated from the use of the value by multiple tests which could moot the need to compute it. Move the computation down to where it's needed. This also saves a local register to hold the computed value. Signed-off-by: George Spelvin <lkml@sdf.org> Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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