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- /* 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 ([email protected])
- *
- * 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 */
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