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authorDavid Howells <dhowells@redhat.com>2009-04-03 16:42:39 +0100
committerDavid Howells <dhowells@redhat.com>2009-04-03 16:42:39 +0100
commitb510882281d56873e1194021643b7c325336f84f (patch)
tree86cd206b0d2b55dc355833ca238d46488161b64c /include/linux/fscache.h
parent952efe7b7840e1c726ae88222245e4efe6bd88f3 (diff)
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FS-Cache: Implement data I/O part of netfs API
Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
Diffstat (limited to 'include/linux/fscache.h')
-rw-r--r--include/linux/fscache.h52
1 files changed, 47 insertions, 5 deletions
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 245b48646efa..6d8ee466e0a0 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -184,6 +184,24 @@ extern struct fscache_cookie *__fscache_acquire_cookie(
void *);
extern void __fscache_relinquish_cookie(struct fscache_cookie *, int);
extern void __fscache_update_cookie(struct fscache_cookie *);
+extern int __fscache_attr_changed(struct fscache_cookie *);
+extern int __fscache_read_or_alloc_page(struct fscache_cookie *,
+ struct page *,
+ fscache_rw_complete_t,
+ void *,
+ gfp_t);
+extern int __fscache_read_or_alloc_pages(struct fscache_cookie *,
+ struct address_space *,
+ struct list_head *,
+ unsigned *,
+ fscache_rw_complete_t,
+ void *,
+ gfp_t);
+extern int __fscache_alloc_page(struct fscache_cookie *, struct page *, gfp_t);
+extern int __fscache_write_page(struct fscache_cookie *, struct page *, gfp_t);
+extern void __fscache_uncache_page(struct fscache_cookie *, struct page *);
+extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *);
+extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *);
/**
* fscache_register_netfs - Register a filesystem as desiring caching services
@@ -361,7 +379,10 @@ void fscache_unpin_cookie(struct fscache_cookie *cookie)
static inline
int fscache_attr_changed(struct fscache_cookie *cookie)
{
- return -ENOBUFS;
+ if (fscache_cookie_valid(cookie))
+ return __fscache_attr_changed(cookie);
+ else
+ return -ENOBUFS;
}
/**
@@ -418,7 +439,11 @@ int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
void *context,
gfp_t gfp)
{
- return -ENOBUFS;
+ if (fscache_cookie_valid(cookie))
+ return __fscache_read_or_alloc_page(cookie, page, end_io_func,
+ context, gfp);
+ else
+ return -ENOBUFS;
}
/**
@@ -464,7 +489,12 @@ int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
void *context,
gfp_t gfp)
{
- return -ENOBUFS;
+ if (fscache_cookie_valid(cookie))
+ return __fscache_read_or_alloc_pages(cookie, mapping, pages,
+ nr_pages, end_io_func,
+ context, gfp);
+ else
+ return -ENOBUFS;
}
/**
@@ -490,7 +520,10 @@ int fscache_alloc_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
- return -ENOBUFS;
+ if (fscache_cookie_valid(cookie))
+ return __fscache_alloc_page(cookie, page, gfp);
+ else
+ return -ENOBUFS;
}
/**
@@ -516,7 +549,10 @@ int fscache_write_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp)
{
- return -ENOBUFS;
+ if (fscache_cookie_valid(cookie))
+ return __fscache_write_page(cookie, page, gfp);
+ else
+ return -ENOBUFS;
}
/**
@@ -537,6 +573,8 @@ static inline
void fscache_uncache_page(struct fscache_cookie *cookie,
struct page *page)
{
+ if (fscache_cookie_valid(cookie))
+ __fscache_uncache_page(cookie, page);
}
/**
@@ -553,6 +591,8 @@ static inline
bool fscache_check_page_write(struct fscache_cookie *cookie,
struct page *page)
{
+ if (fscache_cookie_valid(cookie))
+ return __fscache_check_page_write(cookie, page);
return false;
}
@@ -571,6 +611,8 @@ static inline
void fscache_wait_on_page_write(struct fscache_cookie *cookie,
struct page *page)
{
+ if (fscache_cookie_valid(cookie))
+ __fscache_wait_on_page_write(cookie, page);
}
#endif /* _LINUX_FSCACHE_H */