diff options
Diffstat (limited to 'include/linux/netfs.h')
| -rw-r--r-- | include/linux/netfs.h | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/include/linux/netfs.h b/include/linux/netfs.h index 8479d63406f7..59e926e62d2e 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -14,6 +14,8 @@ #ifndef _LINUX_NETFS_H #define _LINUX_NETFS_H +#include <linux/workqueue.h> +#include <linux/fs.h> #include <linux/pagemap.h> /* @@ -83,4 +85,85 @@ static inline int wait_on_page_fscache_killable(struct page *page) return wait_on_page_private_2_killable(page); } +enum netfs_read_source { + NETFS_FILL_WITH_ZEROES, + NETFS_DOWNLOAD_FROM_SERVER, + NETFS_READ_FROM_CACHE, + NETFS_INVALID_READ, +} __mode(byte); + +/* + * Descriptor for a single component subrequest. + */ +struct netfs_read_subrequest { + struct netfs_read_request *rreq; /* Supervising read request */ + struct list_head rreq_link; /* Link in rreq->subrequests */ + loff_t start; /* Where to start the I/O */ + size_t len; /* Size of the I/O */ + size_t transferred; /* Amount of data transferred */ + refcount_t usage; + short error; /* 0 or error that occurred */ + unsigned short debug_index; /* Index in list (for debugging output) */ + enum netfs_read_source source; /* Where to read from */ + unsigned long flags; +#define NETFS_SREQ_WRITE_TO_CACHE 0 /* Set if should write to cache */ +#define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */ +#define NETFS_SREQ_SHORT_READ 2 /* Set if there was a short read from the cache */ +#define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */ +#define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */ +}; + +/* + * Descriptor for a read helper request. This is used to make multiple I/O + * requests on a variety of sources and then stitch the result together. + */ +struct netfs_read_request { + struct work_struct work; + struct inode *inode; /* The file being accessed */ + struct address_space *mapping; /* The mapping being accessed */ + struct list_head subrequests; /* Requests to fetch I/O from disk or net */ + void *netfs_priv; /* Private data for the netfs */ + unsigned int debug_id; + atomic_t nr_rd_ops; /* Number of read ops in progress */ + size_t submitted; /* Amount submitted for I/O so far */ + size_t len; /* Length of the request */ + short error; /* 0 or error that occurred */ + loff_t i_size; /* Size of the file */ + loff_t start; /* Start position */ + pgoff_t no_unlock_page; /* Don't unlock this page after read */ + refcount_t usage; + unsigned long flags; +#define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */ +#define NETFS_RREQ_WRITE_TO_CACHE 1 /* Need to write to the cache */ +#define NETFS_RREQ_NO_UNLOCK_PAGE 2 /* Don't unlock no_unlock_page on completion */ +#define NETFS_RREQ_DONT_UNLOCK_PAGES 3 /* Don't unlock the pages on completion */ +#define NETFS_RREQ_FAILED 4 /* The request failed */ +#define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */ + const struct netfs_read_request_ops *netfs_ops; +}; + +/* + * Operations the network filesystem can/must provide to the helpers. + */ +struct netfs_read_request_ops { + void (*init_rreq)(struct netfs_read_request *rreq, struct file *file); + void (*expand_readahead)(struct netfs_read_request *rreq); + bool (*clamp_length)(struct netfs_read_subrequest *subreq); + void (*issue_op)(struct netfs_read_subrequest *subreq); + bool (*is_still_valid)(struct netfs_read_request *rreq); + void (*done)(struct netfs_read_request *rreq); + void (*cleanup)(struct address_space *mapping, void *netfs_priv); +}; + +struct readahead_control; +extern void netfs_readahead(struct readahead_control *, + const struct netfs_read_request_ops *, + void *); +extern int netfs_readpage(struct file *, + struct page *, + const struct netfs_read_request_ops *, + void *); + +extern void netfs_subreq_terminated(struct netfs_read_subrequest *, ssize_t, bool); + #endif /* _LINUX_NETFS_H */ |