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| author | Jeffle Xu <jefflexu@linux.alibaba.com> | 2022-04-25 15:21:27 +0300 |
|---|---|---|
| committer | Gao Xiang <hsiangkao@linux.alibaba.com> | 2022-05-17 19:11:18 +0300 |
| commit | 9032b6e8589f269743984aac53e82e4835be16dc (patch) | |
| tree | cc6b3220d27164f6b39d343a60f5412786db8181 /fs/cachefiles/internal.h | |
| parent | 324b954ac80cff0d11ddb6bde9b6631e45e98620 (diff) | |
| download | linux-9032b6e8589f269743984aac53e82e4835be16dc.tar.xz | |
cachefiles: implement on-demand read
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 <jefflexu@linux.alibaba.com>
Acked-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20220425122143.56815-6-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Diffstat (limited to 'fs/cachefiles/internal.h')
| -rw-r--r-- | fs/cachefiles/internal.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index da388ba127eb..6cba2c6de2f9 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -292,6 +292,9 @@ extern int cachefiles_ondemand_copen(struct cachefiles_cache *cache, extern int cachefiles_ondemand_init_object(struct cachefiles_object *object); extern void cachefiles_ondemand_clean_object(struct cachefiles_object *object); +extern int cachefiles_ondemand_read(struct cachefiles_object *object, + loff_t pos, size_t len); + #else static inline ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache, char __user *_buffer, size_t buflen) @@ -307,6 +310,12 @@ static inline int cachefiles_ondemand_init_object(struct cachefiles_object *obje static inline void cachefiles_ondemand_clean_object(struct cachefiles_object *object) { } + +static inline int cachefiles_ondemand_read(struct cachefiles_object *object, + loff_t pos, size_t len) +{ + return -EOPNOTSUPP; +} #endif /* |