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Diffstat (limited to 'include/linux/netfs.h')
| -rw-r--r-- | include/linux/netfs.h | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/include/linux/netfs.h b/include/linux/netfs.h new file mode 100644 index 000000000..b11a84f6c --- /dev/null +++ b/include/linux/netfs.h @@ -0,0 +1,361 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Network filesystem support services. + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * See: + * + * Documentation/filesystems/netfs_library.rst + * + * for a description of the network filesystem interface declared here. + */ + +#ifndef _LINUX_NETFS_H +#define _LINUX_NETFS_H + +#include <linux/workqueue.h> +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/uio.h> + +enum netfs_sreq_ref_trace; + +/* + * Overload PG_private_2 to give us PG_fscache - this is used to indicate that + * a page is currently backed by a local disk cache + */ +#define folio_test_fscache(folio) folio_test_private_2(folio) +#define PageFsCache(page) PagePrivate2((page)) +#define SetPageFsCache(page) SetPagePrivate2((page)) +#define ClearPageFsCache(page) ClearPagePrivate2((page)) +#define TestSetPageFsCache(page) TestSetPagePrivate2((page)) +#define TestClearPageFsCache(page) TestClearPagePrivate2((page)) + +/** + * folio_start_fscache - Start an fscache write on a folio. + * @folio: The folio. + * + * Call this function before writing a folio to a local cache. Starting a + * second write before the first one finishes is not allowed. + */ +static inline void folio_start_fscache(struct folio *folio) +{ + VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio); + folio_get(folio); + folio_set_private_2(folio); +} + +/** + * folio_end_fscache - End an fscache write on a folio. + * @folio: The folio. + * + * Call this function after the folio has been written to the local cache. + * This will wake any sleepers waiting on this folio. + */ +static inline void folio_end_fscache(struct folio *folio) +{ + folio_end_private_2(folio); +} + +/** + * folio_wait_fscache - Wait for an fscache write on this folio to end. + * @folio: The folio. + * + * If this folio is currently being written to a local cache, wait for + * the write to finish. Another write may start after this one finishes, + * unless the caller holds the folio lock. + */ +static inline void folio_wait_fscache(struct folio *folio) +{ + folio_wait_private_2(folio); +} + +/** + * folio_wait_fscache_killable - Wait for an fscache write on this folio to end. + * @folio: The folio. + * + * If this folio is currently being written to a local cache, wait + * for the write to finish or for a fatal signal to be received. + * Another write may start after this one finishes, unless the caller + * holds the folio lock. + * + * Return: + * - 0 if successful. + * - -EINTR if a fatal signal was encountered. + */ +static inline int folio_wait_fscache_killable(struct folio *folio) +{ + return folio_wait_private_2_killable(folio); +} + +static inline void set_page_fscache(struct page *page) +{ + folio_start_fscache(page_folio(page)); +} + +static inline void end_page_fscache(struct page *page) +{ + folio_end_private_2(page_folio(page)); +} + +static inline void wait_on_page_fscache(struct page *page) +{ + folio_wait_private_2(page_folio(page)); +} + +static inline int wait_on_page_fscache_killable(struct page *page) +{ + return folio_wait_private_2_killable(page_folio(page)); +} + +enum netfs_io_source { + NETFS_FILL_WITH_ZEROES, + NETFS_DOWNLOAD_FROM_SERVER, + NETFS_READ_FROM_CACHE, + NETFS_INVALID_READ, +} __mode(byte); + +typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error, + bool was_async); + +/* + * Per-inode context. This wraps the VFS inode. + */ +struct netfs_inode { + struct inode inode; /* The VFS inode */ + const struct netfs_request_ops *ops; +#if IS_ENABLED(CONFIG_FSCACHE) + struct fscache_cookie *cache; +#endif + loff_t remote_i_size; /* Size of the remote file */ +}; + +/* + * Resources required to do operations on a cache. + */ +struct netfs_cache_resources { + const struct netfs_cache_ops *ops; + void *cache_priv; + void *cache_priv2; + unsigned int debug_id; /* Cookie debug ID */ + unsigned int inval_counter; /* object->inval_counter at begin_op */ +}; + +/* + * Descriptor for a single component subrequest. + */ +struct netfs_io_subrequest { + struct netfs_io_request *rreq; /* Supervising I/O 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 ref; + short error; /* 0 or error that occurred */ + unsigned short debug_index; /* Index in list (for debugging output) */ + enum netfs_io_source source; /* Where to read from/write to */ + unsigned long flags; +#define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */ +#define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */ +#define NETFS_SREQ_SHORT_IO 2 /* Set if the I/O was short */ +#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 */ +#define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */ +}; + +enum netfs_io_origin { + NETFS_READAHEAD, /* This read was triggered by readahead */ + NETFS_READPAGE, /* This read is a synchronous read */ + NETFS_READ_FOR_WRITE, /* This read is to prepare a write */ +} __mode(byte); + +/* + * Descriptor for an I/O helper request. This is used to make multiple I/O + * operations to a variety of data stores and then stitch the result together. + */ +struct netfs_io_request { + struct work_struct work; + struct inode *inode; /* The file being accessed */ + struct address_space *mapping; /* The mapping being accessed */ + struct netfs_cache_resources cache_resources; + struct list_head subrequests; /* Contributory I/O operations */ + void *netfs_priv; /* Private data for the netfs */ + unsigned int debug_id; + atomic_t nr_outstanding; /* Number of ops in progress */ + atomic_t nr_copy_ops; /* Number of copy-to-cache 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 */ + enum netfs_io_origin origin; /* Origin of the request */ + loff_t i_size; /* Size of the file */ + loff_t start; /* Start position */ + pgoff_t no_unlock_folio; /* Don't unlock this folio after read */ + refcount_t ref; + unsigned long flags; +#define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */ +#define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */ +#define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */ +#define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */ +#define NETFS_RREQ_FAILED 4 /* The request failed */ +#define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */ + const struct netfs_request_ops *netfs_ops; +}; + +/* + * Operations the network filesystem can/must provide to the helpers. + */ +struct netfs_request_ops { + int (*init_request)(struct netfs_io_request *rreq, struct file *file); + void (*free_request)(struct netfs_io_request *rreq); + int (*begin_cache_operation)(struct netfs_io_request *rreq); + + void (*expand_readahead)(struct netfs_io_request *rreq); + bool (*clamp_length)(struct netfs_io_subrequest *subreq); + void (*issue_read)(struct netfs_io_subrequest *subreq); + bool (*is_still_valid)(struct netfs_io_request *rreq); + int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, + struct folio **foliop, void **_fsdata); + void (*done)(struct netfs_io_request *rreq); +}; + +/* + * How to handle reading from a hole. + */ +enum netfs_read_from_hole { + NETFS_READ_HOLE_IGNORE, + NETFS_READ_HOLE_CLEAR, + NETFS_READ_HOLE_FAIL, +}; + +/* + * Table of operations for access to a cache. This is obtained by + * rreq->ops->begin_cache_operation(). + */ +struct netfs_cache_ops { + /* End an operation */ + void (*end_operation)(struct netfs_cache_resources *cres); + + /* Read data from the cache */ + int (*read)(struct netfs_cache_resources *cres, + loff_t start_pos, + struct iov_iter *iter, + enum netfs_read_from_hole read_hole, + netfs_io_terminated_t term_func, + void *term_func_priv); + + /* Write data to the cache */ + int (*write)(struct netfs_cache_resources *cres, + loff_t start_pos, + struct iov_iter *iter, + netfs_io_terminated_t term_func, + void *term_func_priv); + + /* Expand readahead request */ + void (*expand_readahead)(struct netfs_cache_resources *cres, + loff_t *_start, size_t *_len, loff_t i_size); + + /* Prepare a read operation, shortening it to a cached/uncached + * boundary as appropriate. + */ + enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq, + loff_t i_size); + + /* Prepare a write operation, working out what part of the write we can + * actually do. + */ + int (*prepare_write)(struct netfs_cache_resources *cres, + loff_t *_start, size_t *_len, loff_t i_size, + bool no_space_allocated_yet); + + /* Prepare an on-demand read operation, shortening it to a cached/uncached + * boundary as appropriate. + */ + enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres, + loff_t start, size_t *_len, + loff_t i_size, + unsigned long *_flags, ino_t ino); + + /* Query the occupancy of the cache in a region, returning where the + * next chunk of data starts and how long it is. + */ + int (*query_occupancy)(struct netfs_cache_resources *cres, + loff_t start, size_t len, size_t granularity, + loff_t *_data_start, size_t *_data_len); +}; + +struct readahead_control; +void netfs_readahead(struct readahead_control *); +int netfs_read_folio(struct file *, struct folio *); +int netfs_write_begin(struct netfs_inode *, struct file *, + struct address_space *, loff_t pos, unsigned int len, + struct folio **, void **fsdata); + +void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool); +void netfs_get_subrequest(struct netfs_io_subrequest *subreq, + enum netfs_sreq_ref_trace what); +void netfs_put_subrequest(struct netfs_io_subrequest *subreq, + bool was_async, enum netfs_sreq_ref_trace what); +void netfs_stats_show(struct seq_file *); +ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len, + struct iov_iter *new, + iov_iter_extraction_t extraction_flags); + +/** + * netfs_inode - Get the netfs inode context from the inode + * @inode: The inode to query + * + * Get the netfs lib inode context from the network filesystem's inode. The + * context struct is expected to directly follow on from the VFS inode struct. + */ +static inline struct netfs_inode *netfs_inode(struct inode *inode) +{ + return container_of(inode, struct netfs_inode, inode); +} + +/** + * netfs_inode_init - Initialise a netfslib inode context + * @ctx: The netfs inode to initialise + * @ops: The netfs's operations list + * + * Initialise the netfs library context struct. This is expected to follow on + * directly from the VFS inode struct. + */ +static inline void netfs_inode_init(struct netfs_inode *ctx, + const struct netfs_request_ops *ops) +{ + ctx->ops = ops; + ctx->remote_i_size = i_size_read(&ctx->inode); +#if IS_ENABLED(CONFIG_FSCACHE) + ctx->cache = NULL; +#endif +} + +/** + * netfs_resize_file - Note that a file got resized + * @ctx: The netfs inode being resized + * @new_i_size: The new file size + * + * Inform the netfs lib that a file got resized so that it can adjust its state. + */ +static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size) +{ + ctx->remote_i_size = new_i_size; +} + +/** + * netfs_i_cookie - Get the cache cookie from the inode + * @ctx: The netfs inode to query + * + * Get the caching cookie (if enabled) from the network filesystem's inode. + */ +static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx) +{ +#if IS_ENABLED(CONFIG_FSCACHE) + return ctx->cache; +#else + return NULL; +#endif +} + +#endif /* _LINUX_NETFS_H */ |