c838305450
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 <jefflexu@linux.alibaba.com> Link: https://lore.kernel.org/r/20220509074028.74954-3-jefflexu@linux.alibaba.com Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
22 lines
380 B
Makefile
22 lines
380 B
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Makefile for caching in a mounted filesystem
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#
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cachefiles-y := \
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cache.o \
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daemon.o \
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interface.o \
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io.o \
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key.o \
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main.o \
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namei.o \
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security.o \
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volume.o \
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xattr.o
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cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o
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cachefiles-$(CONFIG_CACHEFILES_ONDEMAND) += ondemand.o
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obj-$(CONFIG_CACHEFILES) := cachefiles.o
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