user/sven/linux.git/fs/cachefiles, branch v5.19.8

cachefiles: make on-demand request distribution fairer

2022-09-08T09:24:00Z

[ Upstream commit 1122f40072731525c06b1371cfa30112b9b54d27 ] For now, enqueuing and dequeuing on-demand requests all start from idx 0, this makes request distribution unfair. In the weighty concurrent I/O scenario, the request stored in higher idx will starve. Searching requests cyclically in cachefiles_ondemand_daemon_read, makes distribution fairer. Fixes: c8383054506c ("cachefiles: notify the user daemon when looking up cookie") Reported-by: Yongqing Li Signed-off-by: Xin Yin Signed-off-by: David Howells Reviewed-by: Jeffle Xu Reviewed-by: Gao Xiang Link: https://lore.kernel.org/r/20220817065200.11543-1-yinxin.x@bytedance.com/ # v1 Link: https://lore.kernel.org/r/20220825020945.2293-1-yinxin.x@bytedance.com/ # v2 Signed-off-by: Sasha Levin

cachefiles: fix error return code in cachefiles_ondemand_copen()

2022-09-08T09:24:00Z

[ Upstream commit c93ccd63b18c8d108c57b2bb0e5f3b058b9d2029 ] The cache_size field of copen is specified by the user daemon. If cache_size < 0, then the OPEN request is expected to fail, while copen itself shall succeed. However, returning 0 is indeed unexpected when cache_size is an invalid error code. Fix this by returning error when cache_size is an invalid error code. Changes ======= v4: update the code suggested by Dan v3: update the commit log suggested by Jingbo. Fixes: c8383054506c ("cachefiles: notify the user daemon when looking up cookie") Signed-off-by: Sun Ke Suggested-by: Jeffle Xu Suggested-by: Dan Carpenter Signed-off-by: David Howells Reviewed-by: Gao Xiang Reviewed-by: Jingbo Xu Reviewed-by: Dan Carpenter Link: https://lore.kernel.org/r/20220818111935.1683062-1-sunke32@huawei.com/ # v2 Link: https://lore.kernel.org/r/20220818125038.2247720-1-sunke32@huawei.com/ # v3 Link: https://lore.kernel.org/r/20220826023515.3437469-1-sunke32@huawei.com/ # v4 Signed-off-by: Sasha Levin

cachefiles: narrow the scope of flushed requests when releasing fd

2022-07-05T15:12:21Z

When an anonymous fd is released, only flush the requests associated with it, rather than all of requests in xarray. Fixes: 9032b6e8589f ("cachefiles: implement on-demand read") Signed-off-by: Jia Zhu Signed-off-by: David Howells Reviewed-by: Jeffle Xu Reviewed-by: Gao Xiang Link: https://listman.redhat.com/archives/linux-cachefs/2022-June/006937.html

cachefiles: add tracepoints for on-demand read mode

2022-05-17T16:11:18Z

Add tracepoints for on-demand read mode. Currently following tracepoints are added: OPEN request / COPEN reply CLOSE request READ request / CREAD reply write through anonymous fd release of anonymous fd Signed-off-by: Jeffle Xu Acked-by: David Howells Link: https://lore.kernel.org/r/20220425122143.56815-8-jefflexu@linux.alibaba.com Signed-off-by: Gao Xiang

cachefiles: enable on-demand read mode

2022-05-17T16:11:18Z

Enable on-demand read mode by adding an optional parameter to the "bind" command. On-demand mode will be turned on when this parameter is "ondemand", i.e. "bind ondemand". Otherwise cachefiles will work in the original mode. Signed-off-by: Jeffle Xu Link: https://lore.kernel.org/r/20220509074028.74954-7-jefflexu@linux.alibaba.com Acked-by: David Howells Signed-off-by: Gao Xiang

cachefiles: implement on-demand read

2022-05-17T16:11:18Z

Implement the data plane of on-demand read mode. The early implementation [1] place the entry to cachefiles_ondemand_read() in fscache_read(). However, fscache_read() can only detect if the requested file range is fully cache miss, whilst we need to notify the user daemon as long as there's a hole inside the requested file range. Thus the entry is now placed in cachefiles_prepare_read(). When working in on-demand read mode, once a hole detected, the read routine will send a READ request to the user daemon. The user daemon needs to fetch the data and write it to the cache file. After sending the READ request, the read routine will hang there, until the READ request is handled by the user daemon. Then it will retry to read from the same file range. If no progress encountered, the read routine will fail then. A new NETFS_SREQ_ONDEMAND flag is introduced to indicate that on-demand read should be done when a cache miss encountered. [1] https://lore.kernel.org/all/20220406075612.60298-6-jefflexu@linux.alibaba.com/ #v8 Signed-off-by: Jeffle Xu Acked-by: David Howells Link: https://lore.kernel.org/r/20220425122143.56815-6-jefflexu@linux.alibaba.com Signed-off-by: Gao Xiang

cachefiles: notify the user daemon when withdrawing cookie

2022-05-17T16:11:17Z

Notify the user daemon that cookie is going to be withdrawn, providing a hint that the associated anonymous fd can be closed. Be noted that this is only a hint. The user daemon may close the associated anonymous fd when receiving the CLOSE request, then it will receive another anonymous fd when the cookie gets looked up. Or it may ignore the CLOSE request, and keep writing data through the anonymous fd. However the next time the cookie gets looked up, the user daemon will still receive another new anonymous fd. Signed-off-by: Jeffle Xu Acked-by: David Howells Link: https://lore.kernel.org/r/20220425122143.56815-5-jefflexu@linux.alibaba.com Signed-off-by: Gao Xiang

cachefiles: unbind cachefiles gracefully in on-demand mode

2022-05-17T16:11:17Z

Add a refcount to avoid the deadlock in on-demand read mode. The on-demand read mode will pin the corresponding cachefiles object for each anonymous fd. The cachefiles object is unpinned when the anonymous fd gets closed. When the user daemon exits and the fd of "/dev/cachefiles" device node gets closed, it will wait for all cahcefiles objects getting withdrawn. Then if there's any anonymous fd getting closed after the fd of the device node, the user daemon will hang forever, waiting for all objects getting withdrawn. To fix this, add a refcount indicating if there's any object pinned by anonymous fds. The cachefiles cache gets unbound and withdrawn when the refcount is decreased to 0. It won't change the behaviour of the original mode, in which case the cachefiles cache gets unbound and withdrawn as long as the fd of the device node gets closed. Signed-off-by: Jeffle Xu Link: https://lore.kernel.org/r/20220509074028.74954-4-jefflexu@linux.alibaba.com Acked-by: David Howells Signed-off-by: Gao Xiang

cachefiles: notify the user daemon when looking up cookie

2022-05-17T16:11:17Z

Fscache/CacheFiles used to serve as a local cache for a remote networking fs. A new on-demand read mode will be introduced for CacheFiles, which can boost the scenario where on-demand read semantics are needed, e.g. container image distribution. The essential difference between these two modes is seen when a cache miss occurs: In the original mode, the netfs will fetch the data from the remote server and then write it to the cache file; in on-demand read mode, fetching the data and writing it into the cache is delegated to a user daemon. As the first step, notify the user daemon when looking up cookie. In this case, an anonymous fd is sent to the user daemon, through which the user daemon can write the fetched data to the cache file. Since the user daemon may move the anonymous fd around, e.g. through dup(), an object ID uniquely identifying the cache file is also attached. Also add one advisory flag (FSCACHE_ADV_WANT_CACHE_SIZE) suggesting that the cache file size shall be retrieved at runtime. This helps the scenario where one cache file contains multiple netfs files, e.g. for the purpose of deduplication. In this case, netfs itself has no idea the size of the cache file, whilst the user daemon should give the hint on it. Signed-off-by: Jeffle Xu Link: https://lore.kernel.org/r/20220509074028.74954-3-jefflexu@linux.alibaba.com Acked-by: David Howells Signed-off-by: Gao Xiang

cachefiles: extract write routine

2022-05-17T16:11:17Z

Extract the generic routine of writing data to cache files, and make it generally available. This will be used by the following patch implementing on-demand read mode. Since it's called inside CacheFiles module, make the interface generic and unrelated to netfs_cache_resources. It is worth noting that, ki->inval_counter is not initialized after this cleanup. It shall not make any visible difference, since inval_counter is no longer used in the write completion routine, i.e. cachefiles_write_complete(). Signed-off-by: Jeffle Xu Acked-by: David Howells Link: https://lore.kernel.org/r/20220425122143.56815-2-jefflexu@linux.alibaba.com Signed-off-by: Gao Xiang