| /* 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> |
| |
| 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); |
| |
| /* 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 *); |
| |
| /** |
| * 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 */ |