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
  22 enum netfs_sreq_ref_trace;
  23 typedef struct mempool_s mempool_t;
  24
  25 /**
  26  * folio_start_private_2 - Start an fscache write on a folio.  [DEPRECATED]
  27  * @folio: The folio.
  28  *
  29  * Call this function before writing a folio to a local cache.  Starting a
  30  * second write before the first one finishes is not allowed.
  31  *
  32  * Note that this should no longer be used.
  33  */
  34 static inline void folio_start_private_2(struct folio *folio)
  35 {
  36         VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
  37         folio_get(folio);
  38         folio_set_private_2(folio);
  39 }
  40
  41 enum netfs_io_source {
  42         NETFS_SOURCE_UNKNOWN,
  43         NETFS_FILL_WITH_ZEROES,
  44         NETFS_DOWNLOAD_FROM_SERVER,
  45         NETFS_READ_FROM_CACHE,
  46         NETFS_INVALID_READ,
  47         NETFS_UPLOAD_TO_SERVER,
  48         NETFS_WRITE_TO_CACHE,
  49         NETFS_INVALID_WRITE,
  50 } __mode(byte);
  51
  52 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
  53                                       bool was_async);
  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_WRITETHROUGH 2               /* Write-through caching */
  73 #define NETFS_ICTX_MODIFIED_ATTR 3              /* Indicate change in mtime/ctime */
  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         enum netfs_io_source    source;         /* Where to read from/write to */
 147         unsigned short          error;          /* Aggregate error for the stream */
 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         size_t                  consumed;       /* Amount of read data consumed */
 182         size_t                  prev_donated;   /* Amount of data donated from previous subreq */
 183         size_t                  next_donated;   /* Amount of data donated from next subreq */
 184         refcount_t              ref;
 185         short                   error;          /* 0 or error that occurred */
 186         unsigned short          debug_index;    /* Index in list (for debugging output) */
 187         unsigned int            nr_segs;        /* Number of segs in io_iter */
 188         enum netfs_io_source    source;         /* Where to read from/write to */
 189         unsigned char           stream_nr;      /* I/O stream this belongs to */
 190         unsigned char           curr_folioq_slot; /* Folio currently being read */
 191         unsigned char           curr_folio_order; /* Order of folio */
 192         struct folio_queue      *curr_folioq;   /* Queue segment in which current folio resides */
 193         unsigned long           flags;
 194 #define NETFS_SREQ_COPY_TO_CACHE        0       /* Set if should copy the data to the cache */
 195 #define NETFS_SREQ_CLEAR_TAIL           1       /* Set if the rest of the read should be cleared */
 196 #define NETFS_SREQ_SEEK_DATA_READ       3       /* Set if ->read() should SEEK_DATA first */
 197 #define NETFS_SREQ_NO_PROGRESS          4       /* Set if we didn't manage to read any data */
 198 #define NETFS_SREQ_ONDEMAND             5       /* Set if it's from on-demand read mode */
 199 #define NETFS_SREQ_BOUNDARY             6       /* Set if ends on hard boundary (eg. ceph object) */
 200 #define NETFS_SREQ_HIT_EOF              7       /* Set if short due to EOF */
 201 #define NETFS_SREQ_IN_PROGRESS          8       /* Unlocked when the subrequest completes */
 202 #define NETFS_SREQ_NEED_RETRY           9       /* Set if the filesystem requests a retry */
 203 #define NETFS_SREQ_RETRYING             10      /* Set if we're retrying */
 204 #define NETFS_SREQ_FAILED               11      /* Set if the subreq failed unretryably */
 205 };
 206
 207 enum netfs_io_origin {
 208         NETFS_READAHEAD,                /* This read was triggered by readahead */
 209         NETFS_READPAGE,                 /* This read is a synchronous read */
 210         NETFS_READ_GAPS,                /* This read is a synchronous read to fill gaps */
 211         NETFS_READ_FOR_WRITE,           /* This read is to prepare a write */
 212         NETFS_DIO_READ,                 /* This is a direct I/O read */
 213         NETFS_WRITEBACK,                /* This write was triggered by writepages */
 214         NETFS_WRITETHROUGH,             /* This write was made by netfs_perform_write() */
 215         NETFS_UNBUFFERED_WRITE,         /* This is an unbuffered write */
 216         NETFS_DIO_WRITE,                /* This is a direct I/O write */
 217         NETFS_PGPRIV2_COPY_TO_CACHE,    /* [DEPRECATED] This is writing read data to the cache */
 218         nr__netfs_io_origin
 219 } __mode(byte);
 220
 221 /*
 222  * Descriptor for an I/O helper request.  This is used to make multiple I/O
 223  * operations to a variety of data stores and then stitch the result together.
 224  */
 225 struct netfs_io_request {
 226         union {
 227                 struct work_struct work;
 228                 struct rcu_head rcu;
 229         };
 230         struct inode            *inode;         /* The file being accessed */
 231         struct address_space    *mapping;       /* The mapping being accessed */
 232         struct kiocb            *iocb;          /* AIO completion vector */
 233         struct netfs_cache_resources cache_resources;
 234         struct readahead_control *ractl;        /* Readahead descriptor */
 235         struct list_head        proc_link;      /* Link in netfs_iorequests */
 236         struct list_head        subrequests;    /* Contributory I/O operations */
 237         struct netfs_io_stream  io_streams[2];  /* Streams of parallel I/O operations */
 238 #define NR_IO_STREAMS 2 //wreq->nr_io_streams
 239         struct netfs_group      *group;         /* Writeback group being written back */
 240         struct folio_queue      *buffer;        /* Head of I/O buffer */
 241         struct folio_queue      *buffer_tail;   /* Tail of I/O buffer */
 242         struct iov_iter         iter;           /* Unencrypted-side iterator */
 243         struct iov_iter         io_iter;        /* I/O (Encrypted-side) iterator */
 244         void                    *netfs_priv;    /* Private data for the netfs */
 245         void                    *netfs_priv2;   /* Private data for the netfs */
 246         struct bio_vec          *direct_bv;     /* DIO buffer list (when handling iovec-iter) */
 247         unsigned int            direct_bv_count; /* Number of elements in direct_bv[] */
 248         unsigned int            debug_id;
 249         unsigned int            rsize;          /* Maximum read size (0 for none) */
 250         unsigned int            wsize;          /* Maximum write size (0 for none) */
 251         atomic_t                subreq_counter; /* Next subreq->debug_index */
 252         unsigned int            nr_group_rel;   /* Number of refs to release on ->group */
 253         spinlock_t              lock;           /* Lock for queuing subreqs */
 254         atomic_t                nr_outstanding; /* Number of ops in progress */
 255         unsigned long long      submitted;      /* Amount submitted for I/O so far */
 256         unsigned long long      len;            /* Length of the request */
 257         size_t                  transferred;    /* Amount to be indicated as transferred */
 258         long                    error;          /* 0 or error that occurred */
 259         enum netfs_io_origin    origin;         /* Origin of the request */
 260         bool                    direct_bv_unpin; /* T if direct_bv[] must be unpinned */
 261         u8                      buffer_head_slot; /* First slot in ->buffer */
 262         u8                      buffer_tail_slot; /* Next slot in ->buffer_tail */
 263         unsigned long long      i_size;         /* Size of the file */
 264         unsigned long long      start;          /* Start position */
 265         atomic64_t              issued_to;      /* Write issuer folio cursor */
 266         unsigned long long      collected_to;   /* Point we've collected to */
 267         unsigned long long      cleaned_to;     /* Position we've cleaned folios to */
 268         pgoff_t                 no_unlock_folio; /* Don't unlock this folio after read */
 269         size_t                  prev_donated;   /* Fallback for subreq->prev_donated */
 270         refcount_t              ref;
 271         unsigned long           flags;
 272 #define NETFS_RREQ_COPY_TO_CACHE        1       /* Need to write to the cache */
 273 #define NETFS_RREQ_NO_UNLOCK_FOLIO      2       /* Don't unlock no_unlock_folio on completion */
 274 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS   3       /* Don't unlock the folios on completion */
 275 #define NETFS_RREQ_FAILED               4       /* The request failed */
 276 #define NETFS_RREQ_IN_PROGRESS          5       /* Unlocked when the request completes */
 277 #define NETFS_RREQ_UPLOAD_TO_SERVER     8       /* Need to write to the server */
 278 #define NETFS_RREQ_NONBLOCK             9       /* Don't block if possible (O_NONBLOCK) */
 279 #define NETFS_RREQ_BLOCKED              10      /* We blocked */
 280 #define NETFS_RREQ_PAUSE                11      /* Pause subrequest generation */
 281 #define NETFS_RREQ_USE_IO_ITER          12      /* Use ->io_iter rather than ->i_pages */
 282 #define NETFS_RREQ_ALL_QUEUED           13      /* All subreqs are now queued */
 283 #define NETFS_RREQ_NEED_RETRY           14      /* Need to try retrying */
 284 #define NETFS_RREQ_USE_PGPRIV2          31      /* [DEPRECATED] Use PG_private_2 to mark
 285                                                  * write to cache on read */
 286         const struct netfs_request_ops *netfs_ops;
 287         void (*cleanup)(struct netfs_io_request *req);
 288 };
 289
 290 /*
 291  * Operations the network filesystem can/must provide to the helpers.
 292  */
 293 struct netfs_request_ops {
 294         mempool_t *request_pool;
 295         mempool_t *subrequest_pool;
 296         int (*init_request)(struct netfs_io_request *rreq, struct file *file);
 297         void (*free_request)(struct netfs_io_request *rreq);
 298         void (*free_subrequest)(struct netfs_io_subrequest *rreq);
 299
 300         /* Read request handling */
 301         void (*expand_readahead)(struct netfs_io_request *rreq);
 302         int (*prepare_read)(struct netfs_io_subrequest *subreq);
 303         void (*issue_read)(struct netfs_io_subrequest *subreq);
 304         bool (*is_still_valid)(struct netfs_io_request *rreq);
 305         int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
 306                                  struct folio **foliop, void **_fsdata);
 307         void (*done)(struct netfs_io_request *rreq);
 308
 309         /* Modification handling */
 310         void (*update_i_size)(struct inode *inode, loff_t i_size);
 311         void (*post_modify)(struct inode *inode);
 312
 313         /* Write request handling */
 314         void (*begin_writeback)(struct netfs_io_request *wreq);
 315         void (*prepare_write)(struct netfs_io_subrequest *subreq);
 316         void (*issue_write)(struct netfs_io_subrequest *subreq);
 317         void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
 318         void (*invalidate_cache)(struct netfs_io_request *wreq);
 319 };
 320
 321 /*
 322  * How to handle reading from a hole.
 323  */
 324 enum netfs_read_from_hole {
 325         NETFS_READ_HOLE_IGNORE,
 326         NETFS_READ_HOLE_CLEAR,
 327         NETFS_READ_HOLE_FAIL,
 328 };
 329
 330 /*
 331  * Table of operations for access to a cache.
 332  */
 333 struct netfs_cache_ops {
 334         /* End an operation */
 335         void (*end_operation)(struct netfs_cache_resources *cres);
 336
 337         /* Read data from the cache */
 338         int (*read)(struct netfs_cache_resources *cres,
 339                     loff_t start_pos,
 340                     struct iov_iter *iter,
 341                     enum netfs_read_from_hole read_hole,
 342                     netfs_io_terminated_t term_func,
 343                     void *term_func_priv);
 344
 345         /* Write data to the cache */
 346         int (*write)(struct netfs_cache_resources *cres,
 347                      loff_t start_pos,
 348                      struct iov_iter *iter,
 349                      netfs_io_terminated_t term_func,
 350                      void *term_func_priv);
 351
 352         /* Write data to the cache from a netfs subrequest. */
 353         void (*issue_write)(struct netfs_io_subrequest *subreq);
 354
 355         /* Expand readahead request */
 356         void (*expand_readahead)(struct netfs_cache_resources *cres,
 357                                  unsigned long long *_start,
 358                                  unsigned long long *_len,
 359                                  unsigned long long i_size);
 360
 361         /* Prepare a read operation, shortening it to a cached/uncached
 362          * boundary as appropriate.
 363          */
 364         enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
 365                                              unsigned long long i_size);
 366
 367         /* Prepare a write subrequest, working out if we're allowed to do it
 368          * and finding out the maximum amount of data to gather before
 369          * attempting to submit.  If we're not permitted to do it, the
 370          * subrequest should be marked failed.
 371          */
 372         void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq);
 373
 374         /* Prepare a write operation, working out what part of the write we can
 375          * actually do.
 376          */
 377         int (*prepare_write)(struct netfs_cache_resources *cres,
 378                              loff_t *_start, size_t *_len, size_t upper_len,
 379                              loff_t i_size, bool no_space_allocated_yet);
 380
 381         /* Prepare an on-demand read operation, shortening it to a cached/uncached
 382          * boundary as appropriate.
 383          */
 384         enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
 385                                                       loff_t start, size_t *_len,
 386                                                       loff_t i_size,
 387                                                       unsigned long *_flags, ino_t ino);
 388
 389         /* Query the occupancy of the cache in a region, returning where the
 390          * next chunk of data starts and how long it is.
 391          */
 392         int (*query_occupancy)(struct netfs_cache_resources *cres,
 393                                loff_t start, size_t len, size_t granularity,
 394                                loff_t *_data_start, size_t *_data_len);
 395 };
 396
 397 /* High-level read API. */
 398 ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter);
 399 ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 400 ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 401 ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 402
 403 /* High-level write API */
 404 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 405                             struct netfs_group *netfs_group);
 406 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
 407                                          struct netfs_group *netfs_group);
 408 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);
 409 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
 410                                            struct netfs_group *netfs_group);
 411 ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from);
 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                                 bool was_async);
 434 void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq,
 435                                   int error, bool was_async);
 436 void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
 437                           enum netfs_sreq_ref_trace what);
 438 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
 439                           bool was_async, enum netfs_sreq_ref_trace what);
 440 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
 441                                 struct iov_iter *new,
 442                                 iov_iter_extraction_t extraction_flags);
 443 size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
 444                         size_t max_size, size_t max_segs);
 445 void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq);
 446 void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
 447                                        bool was_async);
 448 void netfs_queue_write_request(struct netfs_io_subrequest *subreq);
 449
 450 int netfs_start_io_read(struct inode *inode);
 451 void netfs_end_io_read(struct inode *inode);
 452 int netfs_start_io_write(struct inode *inode);
 453 void netfs_end_io_write(struct inode *inode);
 454 int netfs_start_io_direct(struct inode *inode);
 455 void netfs_end_io_direct(struct inode *inode);
 456
 457 /**
 458  * netfs_inode - Get the netfs inode context from the inode
 459  * @inode: The inode to query
 460  *
 461  * Get the netfs lib inode context from the network filesystem's inode.  The
 462  * context struct is expected to directly follow on from the VFS inode struct.
 463  */
 464 static inline struct netfs_inode *netfs_inode(struct inode *inode)
 465 {
 466         return container_of(inode, struct netfs_inode, inode);
 467 }
 468
 469 /**
 470  * netfs_inode_init - Initialise a netfslib inode context
 471  * @ctx: The netfs inode to initialise
 472  * @ops: The netfs's operations list
 473  * @use_zero_point: True to use the zero_point read optimisation
 474  *
 475  * Initialise the netfs library context struct.  This is expected to follow on
 476  * directly from the VFS inode struct.
 477  */
 478 static inline void netfs_inode_init(struct netfs_inode *ctx,
 479                                     const struct netfs_request_ops *ops,
 480                                     bool use_zero_point)
 481 {
 482         ctx->ops = ops;
 483         ctx->remote_i_size = i_size_read(&ctx->inode);
 484         ctx->zero_point = LLONG_MAX;
 485         ctx->flags = 0;
 486         atomic_set(&ctx->io_count, 0);
 487 #if IS_ENABLED(CONFIG_FSCACHE)
 488         ctx->cache = NULL;
 489 #endif
 490         mutex_init(&ctx->wb_lock);
 491         /* ->releasepage() drives zero_point */
 492         if (use_zero_point) {
 493                 ctx->zero_point = ctx->remote_i_size;
 494                 mapping_set_release_always(ctx->inode.i_mapping);
 495         }
 496 }
 497
 498 /**
 499  * netfs_resize_file - Note that a file got resized
 500  * @ctx: The netfs inode being resized
 501  * @new_i_size: The new file size
 502  * @changed_on_server: The change was applied to the server
 503  *
 504  * Inform the netfs lib that a file got resized so that it can adjust its state.
 505  */
 506 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size,
 507                                      bool changed_on_server)
 508 {
 509         if (changed_on_server)
 510                 ctx->remote_i_size = new_i_size;
 511         if (new_i_size < ctx->zero_point)
 512                 ctx->zero_point = new_i_size;
 513 }
 514
 515 /**
 516  * netfs_i_cookie - Get the cache cookie from the inode
 517  * @ctx: The netfs inode to query
 518  *
 519  * Get the caching cookie (if enabled) from the network filesystem's inode.
 520  */
 521 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
 522 {
 523 #if IS_ENABLED(CONFIG_FSCACHE)
 524         return ctx->cache;
 525 #else
 526         return NULL;
 527 #endif
 528 }
 529
 530 /**
 531  * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete
 532  * @inode: The netfs inode to wait on
 533  *
 534  * Wait for outstanding I/O requests of any type to complete.  This is intended
 535  * to be called from inode eviction routines.  This makes sure that any
 536  * resources held by those requests are cleaned up before we let the inode get
 537  * cleaned up.
 538  */
 539 static inline void netfs_wait_for_outstanding_io(struct inode *inode)
 540 {
 541         struct netfs_inode *ictx = netfs_inode(inode);
 542
 543         wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);
 544 }
 545
 546 #endif /* _LINUX_NETFS_H */