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