include/linux/netfs.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /* Network filesystem support services.
   3  *
   4  * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  *
   7  * See:
   8  *
   9  *      Documentation/filesystems/netfs_library.rst
  10  *
  11  * for a description of the network filesystem interface declared here.
  12  */
  13
  14 #ifndef _LINUX_NETFS_H
  15 #define _LINUX_NETFS_H
  16
  17 #include <linux/workqueue.h>
  18 #include <linux/fs.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/uio.h>
  21 #include <linux/rolling_buffer.h>
  22
  23 enum netfs_sreq_ref_trace;
  24 typedef struct mempool_s mempool_t;
  25 struct folio_queue;
  26
  27 /**
  28  * folio_start_private_2 - Start an fscache write on a folio.  [DEPRECATED]
  29  * @folio: The folio.
  30  *
  31  * Call this function before writing a folio to a local cache.  Starting a
  32  * second write before the first one finishes is not allowed.
  33  *
  34  * Note that this should no longer be used.
  35  */
  36 static inline void folio_start_private_2(struct folio *folio)
  37 {
  38         VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
  39         folio_get(folio);
  40         folio_set_private_2(folio);
  41 }
  42
  43 enum netfs_io_source {
  44         NETFS_SOURCE_UNKNOWN,
  45         NETFS_FILL_WITH_ZEROES,
  46         NETFS_DOWNLOAD_FROM_SERVER,
  47         NETFS_READ_FROM_CACHE,
  48         NETFS_INVALID_READ,
  49         NETFS_UPLOAD_TO_SERVER,
  50         NETFS_WRITE_TO_CACHE,
  51 } __mode(byte);
  52
  53 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error);
  54
  55 /*
  56  * Per-inode context.  This wraps the VFS inode.
  57  */
  58 struct netfs_inode {
  59         struct inode            inode;          /* The VFS inode */
  60         const struct netfs_request_ops *ops;
  61 #if IS_ENABLED(CONFIG_FSCACHE)
  62         struct fscache_cookie   *cache;
  63 #endif
  64         struct mutex            wb_lock;        /* Writeback serialisation */
  65         loff_t                  remote_i_size;  /* Size of the remote file */
  66         loff_t                  zero_point;     /* Size after which we assume there's no data
  67                                                  * on the server */
  68         atomic_t                io_count;       /* Number of outstanding reqs */
  69         unsigned long           flags;
  70 #define NETFS_ICTX_ODIRECT      0               /* The file has DIO in progress */
  71 #define NETFS_ICTX_UNBUFFERED   1               /* I/O should not use the pagecache */
  72 #define NETFS_ICTX_MODIFIED_ATTR 3              /* Indicate change in mtime/ctime */
  73 #define NETFS_ICTX_SINGLE_NO_UPLOAD 4           /* Monolithic payload, cache but no upload */
  74 };
  75
  76 /*
  77  * A netfs group - for instance a ceph snap.  This is marked on dirty pages and
  78  * pages marked with a group must be flushed before they can be written under
  79  * the domain of another group.
  80  */
  81 struct netfs_group {
  82         refcount_t              ref;
  83         void (*free)(struct netfs_group *netfs_group);
  84 };
  85
  86 /*
  87  * Information about a dirty page (attached only if necessary).
  88  * folio->private
  89  */
  90 struct netfs_folio {
  91         struct netfs_group      *netfs_group;   /* Filesystem's grouping marker (or NULL). */
  92         unsigned int            dirty_offset;   /* Write-streaming dirty data offset */
  93         unsigned int            dirty_len;      /* Write-streaming dirty data length */
  94 };
  95 #define NETFS_FOLIO_INFO        0x1UL   /* OR'd with folio->private. */
  96 #define NETFS_FOLIO_COPY_TO_CACHE ((struct netfs_group *)0x356UL) /* Write to the cache only */
  97
  98 static inline bool netfs_is_folio_info(const void *priv)
  99 {
 100         return (unsigned long)priv & NETFS_FOLIO_INFO;
 101 }
 102
 103 static inline struct netfs_folio *__netfs_folio_info(const void *priv)
 104 {
 105         if (netfs_is_folio_info(priv))
 106                 return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO);
 107         return NULL;
 108 }
 109
 110 static inline struct netfs_folio *netfs_folio_info(struct folio *folio)
 111 {
 112         return __netfs_folio_info(folio_get_private(folio));
 113 }
 114
 115 static inline struct netfs_group *netfs_folio_group(struct folio *folio)
 116 {
 117         struct netfs_folio *finfo;
 118         void *priv = folio_get_private(folio);
 119
 120         finfo = netfs_folio_info(folio);
 121         if (finfo)
 122                 return finfo->netfs_group;
 123         return priv;
 124 }
 125
 126 /*
 127  * Stream of I/O subrequests going to a particular destination, such as the
 128  * server or the local cache.  This is mainly intended for writing where we may
 129  * have to write to multiple destinations concurrently.
 130  */
 131 struct netfs_io_stream {
 132         /* Submission tracking */
 133         struct netfs_io_subrequest *construct;  /* Op being constructed */
 134         size_t                  sreq_max_len;   /* Maximum size of a subrequest */
 135         unsigned int            sreq_max_segs;  /* 0 or max number of segments in an iterator */
 136         unsigned int            submit_off;     /* Folio offset we're submitting from */
 137         unsigned int            submit_len;     /* Amount of data left to submit */
 138         unsigned int            submit_extendable_to; /* Amount I/O can be rounded up to */
 139         void (*prepare_write)(struct netfs_io_subrequest *subreq);
 140         void (*issue_write)(struct netfs_io_subrequest *subreq);
 141         /* Collection tracking */
 142         struct list_head        subrequests;    /* Contributory I/O operations */
 143         struct netfs_io_subrequest *front;      /* Op being collected */
 144         unsigned long long      collected_to;   /* Position we've collected results to */
 145         size_t                  transferred;    /* The amount transferred from this stream */
 146         unsigned short          error;          /* Aggregate error for the stream */
 147         enum netfs_io_source    source;         /* Where to read from/write to */
 148         unsigned char           stream_nr;      /* Index of stream in parent table */
 149         bool                    avail;          /* T if stream is available */
 150         bool                    active;         /* T if stream is active */
 151         bool                    need_retry;     /* T if this stream needs retrying */
 152         bool                    failed;         /* T if this stream failed */
 153 };
 154
 155 /*
 156  * Resources required to do operations on a cache.
 157  */
 158 struct netfs_cache_resources {
 159         const struct netfs_cache_ops    *ops;
 160         void                            *cache_priv;
 161         void                            *cache_priv2;
 162         unsigned int                    debug_id;       /* Cookie debug ID */
 163         unsigned int                    inval_counter;  /* object->inval_counter at begin_op */
 164 };
 165
 166 /*
 167  * Descriptor for a single component subrequest.  Each operation represents an
 168  * individual read/write from/to a server, a cache, a journal, etc..
 169  *
 170  * The buffer iterator is persistent for the life of the subrequest struct and
 171  * the pages it points to can be relied on to exist for the duration.
 172  */
 173 struct netfs_io_subrequest {
 174         struct netfs_io_request *rreq;          /* Supervising I/O request */
 175         struct work_struct      work;
 176         struct list_head        rreq_link;      /* Link in rreq->subrequests */
 177         struct iov_iter         io_iter;        /* Iterator for this subrequest */
 178         unsigned long long      start;          /* Where to start the I/O */
 179         size_t                  len;            /* Size of the I/O */
 180         size_t                  transferred;    /* Amount of data transferred */
 181         refcount_t              ref;
 182         short                   error;          /* 0 or error that occurred */
 183         unsigned short          debug_index;    /* Index in list (for debugging output) */
 184         unsigned int            nr_segs;        /* Number of segs in io_iter */
 185         u8                      retry_count;    /* The number of retries (0 on initial pass) */
 186         enum netfs_io_source    source;         /* Where to read from/write to */
 187         unsigned char           stream_nr;      /* I/O stream this belongs to */
 188         unsigned long           flags;
 189 #define NETFS_SREQ_COPY_TO_CACHE        0       /* Set if should copy the data to the cache */
 190 #define NETFS_SREQ_CLEAR_TAIL           1       /* Set if the rest of the read should be cleared */
 191 #define NETFS_SREQ_MADE_PROGRESS        4       /* Set if we transferred at least some data */
 192 #define NETFS_SREQ_ONDEMAND             5       /* Set if it's from on-demand read mode */
 193 #define NETFS_SREQ_BOUNDARY             6       /* Set if ends on hard boundary (eg. ceph object) */
 194 #define NETFS_SREQ_HIT_EOF              7       /* Set if short due to EOF */
 195 #define NETFS_SREQ_IN_PROGRESS          8       /* Unlocked when the subrequest completes */
 196 #define NETFS_SREQ_NEED_RETRY           9       /* Set if the filesystem requests a retry */
 197 #define NETFS_SREQ_FAILED               10      /* Set if the subreq failed unretryably */
 198 };
 199
 200 enum netfs_io_origin {
 201         NETFS_READAHEAD,                /* This read was triggered by readahead */
 202         NETFS_READPAGE,                 /* This read is a synchronous read */
 203         NETFS_READ_GAPS,                /* This read is a synchronous read to fill gaps */
 204         NETFS_READ_SINGLE,              /* This read should be treated as a single object */
 205         NETFS_READ_FOR_WRITE,           /* This read is to prepare a write */
 206         NETFS_UNBUFFERED_READ,          /* This is an unbuffered read */
 207         NETFS_DIO_READ,                 /* This is a direct I/O read */
 208         NETFS_WRITEBACK,                /* This write was triggered by writepages */
 209         NETFS_WRITEBACK_SINGLE,         /* This monolithic write was triggered by writepages */
 210         NETFS_WRITETHROUGH,             /* This write was made by netfs_perform_write() */
 211         NETFS_UNBUFFERED_WRITE,         /* This is an unbuffered write */
 212         NETFS_DIO_WRITE,                /* This is a direct I/O write */
 213         NETFS_PGPRIV2_COPY_TO_CACHE,    /* [DEPRECATED] This is writing read data to the cache */
 214         nr__netfs_io_origin
 215 } __mode(byte);
 216
 217 /*
 218  * Descriptor for an I/O helper request.  This is used to make multiple I/O
 219  * operations to a variety of data stores and then stitch the result together.
 220  */
 221 struct netfs_io_request {
 222         union {
 223                 struct work_struct cleanup_work; /* Deferred cleanup work */
 224                 struct rcu_head rcu;
 225         };
 226         struct work_struct      work;           /* Result collector work */
 227         struct inode            *inode;         /* The file being accessed */
 228         struct address_space    *mapping;       /* The mapping being accessed */
 229         struct kiocb            *iocb;          /* AIO completion vector */
 230         struct netfs_cache_resources cache_resources;
 231         struct netfs_io_request *copy_to_cache; /* Request to write just-read data to the cache */
 232 #ifdef CONFIG_PROC_FS
 233         struct list_head        proc_link;      /* Link in netfs_iorequests */
 234 #endif
 235         struct netfs_io_stream  io_streams[2];  /* Streams of parallel I/O operations */
 236 #define NR_IO_STREAMS 2 //wreq->nr_io_streams
 237         struct netfs_group      *group;         /* Writeback group being written back */
 238         struct rolling_buffer   buffer;         /* Unencrypted buffer */
 239 #define NETFS_ROLLBUF_PUT_MARK          ROLLBUF_MARK_1
 240 #define NETFS_ROLLBUF_PAGECACHE_MARK    ROLLBUF_MARK_2
 241         wait_queue_head_t       waitq;          /* Processor waiter */
 242         void                    *netfs_priv;    /* Private data for the netfs */
 243         void                    *netfs_priv2;   /* Private data for the netfs */
 244         struct bio_vec          *direct_bv;     /* DIO buffer list (when handling iovec-iter) */
 245         unsigned long long      submitted;      /* Amount submitted for I/O so far */
 246         unsigned long long      len;            /* Length of the request */
 247         size_t                  transferred;    /* Amount to be indicated as transferred */
 248         long                    error;          /* 0 or error that occurred */
 249         unsigned long long      i_size;         /* Size of the file */
 250         unsigned long long      start;          /* Start position */
 251         atomic64_t              issued_to;      /* Write issuer folio cursor */
 252         unsigned long long      collected_to;   /* Point we've collected to */
 253         unsigned long long      cleaned_to;     /* Position we've cleaned folios to */
 254         unsigned long long      abandon_to;     /* Position to abandon folios to */
 255         pgoff_t                 no_unlock_folio; /* Don't unlock this folio after read */
 256         unsigned int            direct_bv_count; /* Number of elements in direct_bv[] */
 257         unsigned int            debug_id;
 258         unsigned int            rsize;          /* Maximum read size (0 for none) */
 259         unsigned int            wsize;          /* Maximum write size (0 for none) */
 260         atomic_t                subreq_counter; /* Next subreq->debug_index */
 261         unsigned int            nr_group_rel;   /* Number of refs to release on ->group */
 262         spinlock_t              lock;           /* Lock for queuing subreqs */
 263         unsigned char           front_folio_order; /* Order (size) of front folio */
 264         enum netfs_io_origin    origin;         /* Origin of the request */
 265         bool                    direct_bv_unpin; /* T if direct_bv[] must be unpinned */
 266         refcount_t              ref;
 267         unsigned long           flags;
 268 #define NETFS_RREQ_IN_PROGRESS          0       /* Unlocked when the request completes (has ref) */
 269 #define NETFS_RREQ_ALL_QUEUED           1       /* All subreqs are now queued */
 270 #define NETFS_RREQ_PAUSE                2       /* Pause subrequest generation */
 271 #define NETFS_RREQ_FAILED               3       /* The request failed */
 272 #define NETFS_RREQ_RETRYING             4       /* Set if we're in the retry path */
 273 #define NETFS_RREQ_SHORT_TRANSFER       5       /* Set if we have a short transfer */
 274 #define NETFS_RREQ_OFFLOAD_COLLECTION   8       /* Offload collection to workqueue */
 275 #define NETFS_RREQ_NO_UNLOCK_FOLIO      9       /* Don't unlock no_unlock_folio on completion */
 276 #define NETFS_RREQ_FOLIO_COPY_TO_CACHE  10      /* Copy current folio to cache from read */
 277 #define NETFS_RREQ_UPLOAD_TO_SERVER     11      /* Need to write to the server */
 278 #define NETFS_RREQ_USE_IO_ITER          12      /* Use ->io_iter rather than ->i_pages */
 279 #define NETFS_RREQ_USE_PGPRIV2          31      /* [DEPRECATED] Use PG_private_2 to mark
 280                                                  * write to cache on read */
 281         const struct netfs_request_ops *netfs_ops;
 282 };
 283
 284 /*
 285  * Operations the network filesystem can/must provide to the helpers.
 286  */
 287 struct netfs_request_ops {
 288         mempool_t *request_pool;
 289         mempool_t *subrequest_pool;
 290         int (*init_request)(struct netfs_io_request *rreq, struct file *file);
 291         void (*free_request)(struct netfs_io_request *rreq);
 292         void (*free_subrequest)(struct netfs_io_subrequest *rreq);
 293
 294         /* Read request handling */
 295         void (*expand_readahead)(struct netfs_io_request *rreq);
 296         int (*prepare_read)(struct netfs_io_subrequest *subreq);
 297         void (*issue_read)(struct netfs_io_subrequest *subreq);
 298         bool (*is_still_valid)(struct netfs_io_request *rreq);
 299         int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
 300                                  struct folio **foliop, void **_fsdata);
 301         void (*done)(struct netfs_io_request *rreq);
 302
 303         /* Modification handling */
 304         void (*update_i_size)(struct inode *inode, loff_t i_size);
 305         void (*post_modify)(struct inode *inode);
 306
 307         /* Write request handling */
 308         void (*begin_writeback)(struct netfs_io_request *wreq);
 309         void (*prepare_write)(struct netfs_io_subrequest *subreq);
 310         void (*issue_write)(struct netfs_io_subrequest *subreq);
 311         void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
 312         void (*invalidate_cache)(struct netfs_io_request *wreq);
 313 };
 314
 315 /*
 316  * How to handle reading from a hole.
 317  */
 318 enum netfs_read_from_hole {
 319         NETFS_READ_HOLE_IGNORE,
 320         NETFS_READ_HOLE_FAIL,
 321 };
 322
 323 /*
 324  * Table of operations for access to a cache.
 325  */
 326 struct netfs_cache_ops {
 327         /* End an operation */
 328         void (*end_operation)(struct netfs_cache_resources *cres);
 329
 330         /* Read data from the cache */
 331         int (*read)(struct netfs_cache_resources *cres,
 332                     loff_t start_pos,
 333                     struct iov_iter *iter,
 334                     enum netfs_read_from_hole read_hole,
 335                     netfs_io_terminated_t term_func,
 336                     void *term_func_priv);
 337
 338         /* Write data to the cache */
 339         int (*write)(struct netfs_cache_resources *cres,
 340                      loff_t start_pos,
 341                      struct iov_iter *iter,
 342                      netfs_io_terminated_t term_func,
 343                      void *term_func_priv);
 344
 345         /* Write data to the cache from a netfs subrequest. */
 346         void (*issue_write)(struct netfs_io_subrequest *subreq);
 347
 348         /* Expand readahead request */
 349         void (*expand_readahead)(struct netfs_cache_resources *cres,
 350                                  unsigned long long *_start,
 351                                  unsigned long long *_len,
 352                                  unsigned long long i_size);
 353
 354         /* Prepare a read operation, shortening it to a cached/uncached
 355          * boundary as appropriate.
 356          */
 357         enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
 358                                              unsigned long long i_size);
 359
 360         /* Prepare a write subrequest, working out if we're allowed to do it
 361          * and finding out the maximum amount of data to gather before
 362          * attempting to submit.  If we're not permitted to do it, the
 363          * subrequest should be marked failed.
 364          */
 365         void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq);
 366
 367         /* Prepare a write operation, working out what part of the write we can
 368          * actually do.
 369          */
 370         int (*prepare_write)(struct netfs_cache_resources *cres,
 371                              loff_t *_start, size_t *_len, size_t upper_len,
 372                              loff_t i_size, bool no_space_allocated_yet);
 373
 374         /* Prepare an on-demand read operation, shortening it to a cached/uncached
 375          * boundary as appropriate.
 376          */
 377         enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
 378                                                       loff_t start, size_t *_len,
 379                                                       loff_t i_size,
 380                                                       unsigned long *_flags, ino_t ino);
 381
 382         /* Query the occupancy of the cache in a region, returning where the
 383          * next chunk of data starts and how long it is.
 384          */
 385         int (*query_occupancy)(struct netfs_cache_resources *cres,
 386                                loff_t start, size_t len, size_t granularity,
 387                                loff_t *_data_start, size_t *_data_len);
 388 };
 389
 390 /* High-level read API. */
 391 ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter);
 392 ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 393 ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 394 ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 395
 396 /* High-level write API */
 397 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 398                             struct netfs_group *netfs_group);
 399 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
 400                                          struct netfs_group *netfs_group);
 401 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);
 402 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
 403                                            struct netfs_group *netfs_group);
 404 ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from);
 405
 406 /* Single, monolithic object read/write API. */
 407 void netfs_single_mark_inode_dirty(struct inode *inode);
 408 ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter);
 409 int netfs_writeback_single(struct address_space *mapping,
 410                            struct writeback_control *wbc,
 411                            struct iov_iter *iter);
 412
 413 /* Address operations API */
 414 struct readahead_control;
 415 void netfs_readahead(struct readahead_control *);
 416 int netfs_read_folio(struct file *, struct folio *);
 417 int netfs_write_begin(struct netfs_inode *, struct file *,
 418                       struct address_space *, loff_t pos, unsigned int len,
 419                       struct folio **, void **fsdata);
 420 int netfs_writepages(struct address_space *mapping,
 421                      struct writeback_control *wbc);
 422 bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio);
 423 int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);
 424 void netfs_clear_inode_writeback(struct inode *inode, const void *aux);
 425 void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
 426 bool netfs_release_folio(struct folio *folio, gfp_t gfp);
 427
 428 /* VMA operations API. */
 429 vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
 430
 431 /* (Sub)request management API. */
 432 void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq);
 433 void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq);
 434 void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
 435                           enum netfs_sreq_ref_trace what);
 436 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
 437                           enum netfs_sreq_ref_trace what);
 438 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
 439                                 struct iov_iter *new,
 440                                 iov_iter_extraction_t extraction_flags);
 441 size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
 442                         size_t max_size, size_t max_segs);
 443 void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq);
 444 void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error);
 445 void netfs_queue_write_request(struct netfs_io_subrequest *subreq);
 446
 447 int netfs_start_io_read(struct inode *inode);
 448 void netfs_end_io_read(struct inode *inode);
 449 int netfs_start_io_write(struct inode *inode);
 450 void netfs_end_io_write(struct inode *inode);
 451 int netfs_start_io_direct(struct inode *inode);
 452 void netfs_end_io_direct(struct inode *inode);
 453
 454 /* Miscellaneous APIs. */
 455 struct folio_queue *netfs_folioq_alloc(unsigned int rreq_id, gfp_t gfp,
 456                                        unsigned int trace /*enum netfs_folioq_trace*/);
 457 void netfs_folioq_free(struct folio_queue *folioq,
 458                        unsigned int trace /*enum netfs_trace_folioq*/);
 459
 460 /* Buffer wrangling helpers API. */
 461 int netfs_alloc_folioq_buffer(struct address_space *mapping,
 462                               struct folio_queue **_buffer,
 463                               size_t *_cur_size, ssize_t size, gfp_t gfp);
 464 void netfs_free_folioq_buffer(struct folio_queue *fq);
 465
 466 /**
 467  * netfs_inode - Get the netfs inode context from the inode
 468  * @inode: The inode to query
 469  *
 470  * Get the netfs lib inode context from the network filesystem's inode.  The
 471  * context struct is expected to directly follow on from the VFS inode struct.
 472  */
 473 static inline struct netfs_inode *netfs_inode(struct inode *inode)
 474 {
 475         return container_of(inode, struct netfs_inode, inode);
 476 }
 477
 478 /**
 479  * netfs_inode_init - Initialise a netfslib inode context
 480  * @ctx: The netfs inode to initialise
 481  * @ops: The netfs's operations list
 482  * @use_zero_point: True to use the zero_point read optimisation
 483  *
 484  * Initialise the netfs library context struct.  This is expected to follow on
 485  * directly from the VFS inode struct.
 486  */
 487 static inline void netfs_inode_init(struct netfs_inode *ctx,
 488                                     const struct netfs_request_ops *ops,
 489                                     bool use_zero_point)
 490 {
 491         ctx->ops = ops;
 492         ctx->remote_i_size = i_size_read(&ctx->inode);
 493         ctx->zero_point = LLONG_MAX;
 494         ctx->flags = 0;
 495         atomic_set(&ctx->io_count, 0);
 496 #if IS_ENABLED(CONFIG_FSCACHE)
 497         ctx->cache = NULL;
 498 #endif
 499         mutex_init(&ctx->wb_lock);
 500         /* ->releasepage() drives zero_point */
 501         if (use_zero_point) {
 502                 ctx->zero_point = ctx->remote_i_size;
 503                 mapping_set_release_always(ctx->inode.i_mapping);
 504         }
 505 }
 506
 507 /**
 508  * netfs_resize_file - Note that a file got resized
 509  * @ctx: The netfs inode being resized
 510  * @new_i_size: The new file size
 511  * @changed_on_server: The change was applied to the server
 512  *
 513  * Inform the netfs lib that a file got resized so that it can adjust its state.
 514  */
 515 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size,
 516                                      bool changed_on_server)
 517 {
 518         if (changed_on_server)
 519                 ctx->remote_i_size = new_i_size;
 520         if (new_i_size < ctx->zero_point)
 521                 ctx->zero_point = new_i_size;
 522 }
 523
 524 /**
 525  * netfs_i_cookie - Get the cache cookie from the inode
 526  * @ctx: The netfs inode to query
 527  *
 528  * Get the caching cookie (if enabled) from the network filesystem's inode.
 529  */
 530 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
 531 {
 532 #if IS_ENABLED(CONFIG_FSCACHE)
 533         return ctx->cache;
 534 #else
 535         return NULL;
 536 #endif
 537 }
 538
 539 /**
 540  * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete
 541  * @inode: The netfs inode to wait on
 542  *
 543  * Wait for outstanding I/O requests of any type to complete.  This is intended
 544  * to be called from inode eviction routines.  This makes sure that any
 545  * resources held by those requests are cleaned up before we let the inode get
 546  * cleaned up.
 547  */
 548 static inline void netfs_wait_for_outstanding_io(struct inode *inode)
 549 {
 550         struct netfs_inode *ictx = netfs_inode(inode);
 551
 552         wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);
 553 }
 554
 555 #endif /* _LINUX_NETFS_H */