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author | David Howells <dhowells@redhat.com> | 2009-11-19 18:11:52 +0000 |
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committer | David Howells <dhowells@redhat.com> | 2009-11-19 18:11:52 +0000 |
commit | a17754fb8c28af19cd70dcbec6d5b0773b94e0c1 (patch) | |
tree | d7c25b217c684153eadbac78ab9b1bbff08b75f6 /include/linux | |
parent | 868411be3f445a83fafbd734f3e426400138add5 (diff) | |
download | linux-stable-a17754fb8c28af19cd70dcbec6d5b0773b94e0c1.tar.gz linux-stable-a17754fb8c28af19cd70dcbec6d5b0773b94e0c1.tar.bz2 linux-stable-a17754fb8c28af19cd70dcbec6d5b0773b94e0c1.zip |
CacheFiles: Don't write a full page if there's only a partial page to cache
cachefiles_write_page() writes a full page to the backing file for the last
page of the netfs file, even if the netfs file's last page is only a partial
page.
This causes the EOF on the backing file to be extended beyond the EOF of the
netfs, and thus the backing file will be truncated by cachefiles_attr_changed()
called from cachefiles_lookup_object().
So we need to limit the write we make to the backing file on that last page
such that it doesn't push the EOF too far.
Also, if a backing file that has a partial page at the end is expanded, we
discard the partial page and refetch it on the basis that we then have a hole
in the file with invalid data, and should the power go out... A better way to
deal with this could be to record a note that the partial page contains invalid
data until the correct data is written into it.
This isn't a problem for netfs's that discard the whole backing file if the
file size changes (such as NFS).
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/fscache-cache.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h index 907bb56c5888..5db50002f3b5 100644 --- a/include/linux/fscache-cache.h +++ b/include/linux/fscache-cache.h @@ -395,6 +395,7 @@ struct fscache_object { struct rb_node objlist_link; /* link in global object list */ #endif pgoff_t store_limit; /* current storage limit */ + loff_t store_limit_l; /* current storage limit */ }; extern const char *fscache_object_states[]; @@ -439,6 +440,7 @@ void fscache_object_init(struct fscache_object *object, object->events = object->event_mask = 0; object->flags = 0; object->store_limit = 0; + object->store_limit_l = 0; object->cache = cache; object->cookie = cookie; object->parent = NULL; @@ -491,6 +493,7 @@ static inline void fscache_object_lookup_error(struct fscache_object *object) static inline void fscache_set_store_limit(struct fscache_object *object, loff_t i_size) { + object->store_limit_l = i_size; object->store_limit = i_size >> PAGE_SHIFT; if (i_size & ~PAGE_MASK) object->store_limit++; |