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         NETFS_INVALID_WRITE,
  52 } __mode(byte);
  53
  54 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
  55                                       bool was_async);
  56
  57 /*
  58  * Per-inode context.  This wraps the VFS inode.
  59  */
  60 struct netfs_inode {
  61         struct inode            inode;          /* The VFS inode */
  62         const struct netfs_request_ops *ops;
  63 #if IS_ENABLED(CONFIG_FSCACHE)
  64         struct fscache_cookie   *cache;
  65 #endif
  66         struct mutex            wb_lock;        /* Writeback serialisation */
  67         loff_t                  remote_i_size;  /* Size of the remote file */
  68         loff_t                  zero_point;     /* Size after which we assume there's no data
  69                                                  * on the server */
  70         atomic_t                io_count;       /* Number of outstanding reqs */
  71         unsigned long           flags;
  72 #define NETFS_ICTX_ODIRECT      0               /* The file has DIO in progress */
  73 #define NETFS_ICTX_UNBUFFERED   1               /* I/O should not use the pagecache */
  74 #define NETFS_ICTX_WRITETHROUGH 2               /* Write-through caching */
  75 #define NETFS_ICTX_MODIFIED_ATTR 3              /* Indicate change in mtime/ctime */
  76 #define NETFS_ICTX_SINGLE_NO_UPLOAD 4           /* Monolithic payload, cache but no upload */
  77 };
  78
  79 /*
  80  * A netfs group - for instance a ceph snap.  This is marked on dirty pages and
  81  * pages marked with a group must be flushed before they can be written under
  82  * the domain of another group.
  83  */
  84 struct netfs_group {
  85         refcount_t              ref;
  86         void (*free)(struct netfs_group *netfs_group);
  87 };
  88
  89 /*
  90  * Information about a dirty page (attached only if necessary).
  91  * folio->private
  92  */
  93 struct netfs_folio {
  94         struct netfs_group      *netfs_group;   /* Filesystem's grouping marker (or NULL). */
  95         unsigned int            dirty_offset;   /* Write-streaming dirty data offset */
  96         unsigned int            dirty_len;      /* Write-streaming dirty data length */
  97 };
  98 #define NETFS_FOLIO_INFO        0x1UL   /* OR'd with folio->private. */
  99 #define NETFS_FOLIO_COPY_TO_CACHE ((struct netfs_group *)0x356UL) /* Write to the cache only */
 100
 101 static inline bool netfs_is_folio_info(const void *priv)
 102 {
 103         return (unsigned long)priv & NETFS_FOLIO_INFO;
 104 }
 105
 106 static inline struct netfs_folio *__netfs_folio_info(const void *priv)
 107 {
 108         if (netfs_is_folio_info(priv))
 109                 return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO);
 110         return NULL;
 111 }
 112
 113 static inline struct netfs_folio *netfs_folio_info(struct folio *folio)
 114 {
 115         return __netfs_folio_info(folio_get_private(folio));
 116 }
 117
 118 static inline struct netfs_group *netfs_folio_group(struct folio *folio)
 119 {
 120         struct netfs_folio *finfo;
 121         void *priv = folio_get_private(folio);
 122
 123         finfo = netfs_folio_info(folio);
 124         if (finfo)
 125                 return finfo->netfs_group;
 126         return priv;
 127 }
 128
 129 /*
 130  * Stream of I/O subrequests going to a particular destination, such as the
 131  * server or the local cache.  This is mainly intended for writing where we may
 132  * have to write to multiple destinations concurrently.
 133  */
 134 struct netfs_io_stream {
 135         /* Submission tracking */
 136         struct netfs_io_subrequest *construct;  /* Op being constructed */
 137         size_t                  sreq_max_len;   /* Maximum size of a subrequest */
 138         unsigned int            sreq_max_segs;  /* 0 or max number of segments in an iterator */
 139         unsigned int            submit_off;     /* Folio offset we're submitting from */
 140         unsigned int            submit_len;     /* Amount of data left to submit */
 141         unsigned int            submit_extendable_to; /* Amount I/O can be rounded up to */
 142         void (*prepare_write)(struct netfs_io_subrequest *subreq);
 143         void (*issue_write)(struct netfs_io_subrequest *subreq);
 144         /* Collection tracking */
 145         struct list_head        subrequests;    /* Contributory I/O operations */
 146         struct netfs_io_subrequest *front;      /* Op being collected */
 147         unsigned long long      collected_to;   /* Position we've collected results to */
 148         size_t                  transferred;    /* The amount transferred from this stream */
 149         enum netfs_io_source    source;         /* Where to read from/write to */
 150         unsigned short          error;          /* Aggregate error for the stream */
 151         unsigned char           stream_nr;      /* Index of stream in parent table */
 152         bool                    avail;          /* T if stream is available */
 153         bool                    active;         /* T if stream is active */
 154         bool                    need_retry;     /* T if this stream needs retrying */
 155         bool                    failed;         /* T if this stream failed */
 156 };
 157
 158 /*
 159  * Resources required to do operations on a cache.
 160  */
 161 struct netfs_cache_resources {
 162         const struct netfs_cache_ops    *ops;
 163         void                            *cache_priv;
 164         void                            *cache_priv2;
 165         unsigned int                    debug_id;       /* Cookie debug ID */
 166         unsigned int                    inval_counter;  /* object->inval_counter at begin_op */
 167 };
 168
 169 /*
 170  * Descriptor for a single component subrequest.  Each operation represents an
 171  * individual read/write from/to a server, a cache, a journal, etc..
 172  *
 173  * The buffer iterator is persistent for the life of the subrequest struct and
 174  * the pages it points to can be relied on to exist for the duration.
 175  */
 176 struct netfs_io_subrequest {
 177         struct netfs_io_request *rreq;          /* Supervising I/O request */
 178         struct work_struct      work;
 179         struct list_head        rreq_link;      /* Link in rreq->subrequests */
 180         struct iov_iter         io_iter;        /* Iterator for this subrequest */
 181         unsigned long long      start;          /* Where to start the I/O */
 182         size_t                  len;            /* Size of the I/O */
 183         size_t                  transferred;    /* Amount of data transferred */
 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         u8                      retry_count;    /* The number of retries (0 on initial pass) */
 189         enum netfs_io_source    source;         /* Where to read from/write to */
 190         unsigned char           stream_nr;      /* I/O stream this belongs to */
 191         unsigned long           flags;
 192 #define NETFS_SREQ_COPY_TO_CACHE        0       /* Set if should copy the data to the cache */
 193 #define NETFS_SREQ_CLEAR_TAIL           1       /* Set if the rest of the read should be cleared */
 194 #define NETFS_SREQ_SEEK_DATA_READ       3       /* Set if ->read() should SEEK_DATA first */
 195 #define NETFS_SREQ_MADE_PROGRESS        4       /* Set if we transferred at least some data */
 196 #define NETFS_SREQ_ONDEMAND             5       /* Set if it's from on-demand read mode */
 197 #define NETFS_SREQ_BOUNDARY             6       /* Set if ends on hard boundary (eg. ceph object) */
 198 #define NETFS_SREQ_HIT_EOF              7       /* Set if short due to EOF */
 199 #define NETFS_SREQ_IN_PROGRESS          8       /* Unlocked when the subrequest completes */
 200 #define NETFS_SREQ_NEED_RETRY           9       /* Set if the filesystem requests a retry */
 201 #define NETFS_SREQ_FAILED               10      /* Set if the subreq failed unretryably */
 202 };
 203
 204 enum netfs_io_origin {
 205         NETFS_READAHEAD,                /* This read was triggered by readahead */
 206         NETFS_READPAGE,                 /* This read is a synchronous read */
 207         NETFS_READ_GAPS,                /* This read is a synchronous read to fill gaps */
 208         NETFS_READ_SINGLE,              /* This read should be treated as a single object */
 209         NETFS_READ_FOR_WRITE,           /* This read is to prepare a write */
 210         NETFS_DIO_READ,                 /* This is a direct I/O read */
 211         NETFS_WRITEBACK,                /* This write was triggered by writepages */
 212         NETFS_WRITEBACK_SINGLE,         /* This monolithic write was triggered by writepages */
 213         NETFS_WRITETHROUGH,             /* This write was made by netfs_perform_write() */
 214         NETFS_UNBUFFERED_WRITE,         /* This is an unbuffered write */
 215         NETFS_DIO_WRITE,                /* This is a direct I/O write */
 216         NETFS_PGPRIV2_COPY_TO_CACHE,    /* [DEPRECATED] This is writing read data to the cache */
 217         nr__netfs_io_origin
 218 } __mode(byte);
 219
 220 /*
 221  * Descriptor for an I/O helper request.  This is used to make multiple I/O
 222  * operations to a variety of data stores and then stitch the result together.
 223  */
 224 struct netfs_io_request {
 225         union {
 226                 struct work_struct work;
 227                 struct rcu_head rcu;
 228         };
 229         struct inode            *inode;         /* The file being accessed */
 230         struct address_space    *mapping;       /* The mapping being accessed */
 231         struct kiocb            *iocb;          /* AIO completion vector */
 232         struct netfs_cache_resources cache_resources;
 233         struct netfs_io_request *copy_to_cache; /* Request to write just-read data to the cache */
 234         struct readahead_control *ractl;        /* Readahead descriptor */
 235         struct list_head        proc_link;      /* Link in netfs_iorequests */
 236         struct netfs_io_stream  io_streams[2];  /* Streams of parallel I/O operations */
 237 #define NR_IO_STREAMS 2 //wreq->nr_io_streams
 238         struct netfs_group      *group;         /* Writeback group being written back */
 239         struct rolling_buffer   buffer;         /* Unencrypted buffer */
 240 #define NETFS_ROLLBUF_PUT_MARK          ROLLBUF_MARK_1
 241 #define NETFS_ROLLBUF_PAGECACHE_MARK    ROLLBUF_MARK_2
 242         wait_queue_head_t       waitq;          /* Processor waiter */
 243         void                    *netfs_priv;    /* Private data for the netfs */
 244         void                    *netfs_priv2;   /* Private data for the netfs */
 245         struct bio_vec          *direct_bv;     /* DIO buffer list (when handling iovec-iter) */
 246         unsigned int            direct_bv_count; /* Number of elements in direct_bv[] */
 247         unsigned int            debug_id;
 248         unsigned int            rsize;          /* Maximum read size (0 for none) */
 249         unsigned int            wsize;          /* Maximum write size (0 for none) */
 250         atomic_t                subreq_counter; /* Next subreq->debug_index */
 251         unsigned int            nr_group_rel;   /* Number of refs to release on ->group */
 252         spinlock_t              lock;           /* Lock for queuing subreqs */
 253         unsigned long long      submitted;      /* Amount submitted for I/O so far */
 254         unsigned long long      len;            /* Length of the request */
 255         size_t                  transferred;    /* Amount to be indicated as transferred */
 256         long                    error;          /* 0 or error that occurred */
 257         enum netfs_io_origin    origin;         /* Origin of the request */
 258         bool                    direct_bv_unpin; /* T if direct_bv[] must be unpinned */
 259         unsigned long long      i_size;         /* Size of the file */
 260         unsigned long long      start;          /* Start position */
 261         atomic64_t              issued_to;      /* Write issuer folio cursor */
 262         unsigned long long      collected_to;   /* Point we've collected to */
 263         unsigned long long      cleaned_to;     /* Position we've cleaned folios to */
 264         unsigned long long      abandon_to;     /* Position to abandon folios to */
 265         pgoff_t                 no_unlock_folio; /* Don't unlock this folio after read */
 266         unsigned char           front_folio_order; /* Order (size) of front folio */
 267         refcount_t              ref;
 268         unsigned long           flags;
 269 #define NETFS_RREQ_OFFLOAD_COLLECTION   0       /* Offload collection to workqueue */
 270 #define NETFS_RREQ_NO_UNLOCK_FOLIO      2       /* Don't unlock no_unlock_folio on completion */
 271 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS   3       /* Don't unlock the folios on completion */
 272 #define NETFS_RREQ_FAILED               4       /* The request failed */
 273 #define NETFS_RREQ_IN_PROGRESS          5       /* Unlocked when the request completes */
 274 #define NETFS_RREQ_FOLIO_COPY_TO_CACHE  6       /* Copy current folio to cache from read */
 275 #define NETFS_RREQ_UPLOAD_TO_SERVER     8       /* Need to write to the server */
 276 #define NETFS_RREQ_NONBLOCK             9       /* Don't block if possible (O_NONBLOCK) */
 277 #define NETFS_RREQ_BLOCKED              10      /* We blocked */
 278 #define NETFS_RREQ_PAUSE                11      /* Pause subrequest generation */
 279 #define NETFS_RREQ_USE_IO_ITER          12      /* Use ->io_iter rather than ->i_pages */
 280 #define NETFS_RREQ_ALL_QUEUED           13      /* All subreqs are now queued */
 281 #define NETFS_RREQ_NEED_RETRY           14      /* Need to try retrying */
 282 #define NETFS_RREQ_USE_PGPRIV2          31      /* [DEPRECATED] Use PG_private_2 to mark
 283                                                  * write to cache on read */
 284         const struct netfs_request_ops *netfs_ops;
 285         void (*cleanup)(struct netfs_io_request *req);
 286 };
 287
 288 /*
 289  * Operations the network filesystem can/must provide to the helpers.
 290  */
 291 struct netfs_request_ops {
 292         mempool_t *request_pool;
 293         mempool_t *subrequest_pool;
 294         int (*init_request)(struct netfs_io_request *rreq, struct file *file);
 295         void (*free_request)(struct netfs_io_request *rreq);
 296         void (*free_subrequest)(struct netfs_io_subrequest *rreq);
 297
 298         /* Read request handling */
 299         void (*expand_readahead)(struct netfs_io_request *rreq);
 300         int (*prepare_read)(struct netfs_io_subrequest *subreq);
 301         void (*issue_read)(struct netfs_io_subrequest *subreq);
 302         bool (*is_still_valid)(struct netfs_io_request *rreq);
 303         int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
 304                                  struct folio **foliop, void **_fsdata);
 305         void (*done)(struct netfs_io_request *rreq);
 306
 307         /* Modification handling */
 308         void (*update_i_size)(struct inode *inode, loff_t i_size);
 309         void (*post_modify)(struct inode *inode);
 310
 311         /* Write request handling */
 312         void (*begin_writeback)(struct netfs_io_request *wreq);
 313         void (*prepare_write)(struct netfs_io_subrequest *subreq);
 314         void (*issue_write)(struct netfs_io_subrequest *subreq);
 315         void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
 316         void (*invalidate_cache)(struct netfs_io_request *wreq);
 317 };
 318
 319 /*
 320  * How to handle reading from a hole.
 321  */
 322 enum netfs_read_from_hole {
 323         NETFS_READ_HOLE_IGNORE,
 324         NETFS_READ_HOLE_CLEAR,
 325         NETFS_READ_HOLE_FAIL,
 326 };
 327
 328 /*
 329  * Table of operations for access to a cache.
 330  */
 331 struct netfs_cache_ops {
 332         /* End an operation */
 333         void (*end_operation)(struct netfs_cache_resources *cres);
 334
 335         /* Read data from the cache */
 336         int (*read)(struct netfs_cache_resources *cres,
 337                     loff_t start_pos,
 338                     struct iov_iter *iter,
 339                     enum netfs_read_from_hole read_hole,
 340                     netfs_io_terminated_t term_func,
 341                     void *term_func_priv);
 342
 343         /* Write data to the cache */
 344         int (*write)(struct netfs_cache_resources *cres,
 345                      loff_t start_pos,
 346                      struct iov_iter *iter,
 347                      netfs_io_terminated_t term_func,
 348                      void *term_func_priv);
 349
 350         /* Write data to the cache from a netfs subrequest. */
 351         void (*issue_write)(struct netfs_io_subrequest *subreq);
 352
 353         /* Expand readahead request */
 354         void (*expand_readahead)(struct netfs_cache_resources *cres,
 355                                  unsigned long long *_start,
 356                                  unsigned long long *_len,
 357                                  unsigned long long i_size);
 358
 359         /* Prepare a read operation, shortening it to a cached/uncached
 360          * boundary as appropriate.
 361          */
 362         enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
 363                                              unsigned long long i_size);
 364
 365         /* Prepare a write subrequest, working out if we're allowed to do it
 366          * and finding out the maximum amount of data to gather before
 367          * attempting to submit.  If we're not permitted to do it, the
 368          * subrequest should be marked failed.
 369          */
 370         void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq);
 371
 372         /* Prepare a write operation, working out what part of the write we can
 373          * actually do.
 374          */
 375         int (*prepare_write)(struct netfs_cache_resources *cres,
 376                              loff_t *_start, size_t *_len, size_t upper_len,
 377                              loff_t i_size, bool no_space_allocated_yet);
 378
 379         /* Prepare an on-demand read operation, shortening it to a cached/uncached
 380          * boundary as appropriate.
 381          */
 382         enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
 383                                                       loff_t start, size_t *_len,
 384                                                       loff_t i_size,
 385                                                       unsigned long *_flags, ino_t ino);
 386
 387         /* Query the occupancy of the cache in a region, returning where the
 388          * next chunk of data starts and how long it is.
 389          */
 390         int (*query_occupancy)(struct netfs_cache_resources *cres,
 391                                loff_t start, size_t len, size_t granularity,
 392                                loff_t *_data_start, size_t *_data_len);
 393 };
 394
 395 /* High-level read API. */
 396 ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter);
 397 ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 398 ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 399 ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 400
 401 /* High-level write API */
 402 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 403                             struct netfs_group *netfs_group);
 404 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
 405                                          struct netfs_group *netfs_group);
 406 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);
 407 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
 408                                            struct netfs_group *netfs_group);
 409 ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from);
 410
 411 /* Single, monolithic object read/write API. */
 412 void netfs_single_mark_inode_dirty(struct inode *inode);
 413 ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter);
 414 int netfs_writeback_single(struct address_space *mapping,
 415                            struct writeback_control *wbc,
 416                            struct iov_iter *iter);
 417
 418 /* Address operations API */
 419 struct readahead_control;
 420 void netfs_readahead(struct readahead_control *);
 421 int netfs_read_folio(struct file *, struct folio *);
 422 int netfs_write_begin(struct netfs_inode *, struct file *,
 423                       struct address_space *, loff_t pos, unsigned int len,
 424                       struct folio **, void **fsdata);
 425 int netfs_writepages(struct address_space *mapping,
 426                      struct writeback_control *wbc);
 427 bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio);
 428 int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);
 429 void netfs_clear_inode_writeback(struct inode *inode, const void *aux);
 430 void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
 431 bool netfs_release_folio(struct folio *folio, gfp_t gfp);
 432
 433 /* VMA operations API. */
 434 vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
 435
 436 /* (Sub)request management API. */
 437 void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq);
 438 void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq);
 439 void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
 440                           enum netfs_sreq_ref_trace what);
 441 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
 442                           bool was_async, enum netfs_sreq_ref_trace what);
 443 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
 444                                 struct iov_iter *new,
 445                                 iov_iter_extraction_t extraction_flags);
 446 size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
 447                         size_t max_size, size_t max_segs);
 448 void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq);
 449 void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
 450                                        bool was_async);
 451 void netfs_queue_write_request(struct netfs_io_subrequest *subreq);
 452
 453 int netfs_start_io_read(struct inode *inode);
 454 void netfs_end_io_read(struct inode *inode);
 455 int netfs_start_io_write(struct inode *inode);
 456 void netfs_end_io_write(struct inode *inode);
 457 int netfs_start_io_direct(struct inode *inode);
 458 void netfs_end_io_direct(struct inode *inode);
 459
 460 /* Miscellaneous APIs. */
 461 struct folio_queue *netfs_folioq_alloc(unsigned int rreq_id, gfp_t gfp,
 462                                        unsigned int trace /*enum netfs_folioq_trace*/);
 463 void netfs_folioq_free(struct folio_queue *folioq,
 464                        unsigned int trace /*enum netfs_trace_folioq*/);
 465
 466 /* Buffer wrangling helpers API. */
 467 int netfs_alloc_folioq_buffer(struct address_space *mapping,
 468                               struct folio_queue **_buffer,
 469                               size_t *_cur_size, ssize_t size, gfp_t gfp);
 470 void netfs_free_folioq_buffer(struct folio_queue *fq);
 471
 472 /**
 473  * netfs_inode - Get the netfs inode context from the inode
 474  * @inode: The inode to query
 475  *
 476  * Get the netfs lib inode context from the network filesystem's inode.  The
 477  * context struct is expected to directly follow on from the VFS inode struct.
 478  */
 479 static inline struct netfs_inode *netfs_inode(struct inode *inode)
 480 {
 481         return container_of(inode, struct netfs_inode, inode);
 482 }
 483
 484 /**
 485  * netfs_inode_init - Initialise a netfslib inode context
 486  * @ctx: The netfs inode to initialise
 487  * @ops: The netfs's operations list
 488  * @use_zero_point: True to use the zero_point read optimisation
 489  *
 490  * Initialise the netfs library context struct.  This is expected to follow on
 491  * directly from the VFS inode struct.
 492  */
 493 static inline void netfs_inode_init(struct netfs_inode *ctx,
 494                                     const struct netfs_request_ops *ops,
 495                                     bool use_zero_point)
 496 {
 497         ctx->ops = ops;
 498         ctx->remote_i_size = i_size_read(&ctx->inode);
 499         ctx->zero_point = LLONG_MAX;
 500         ctx->flags = 0;
 501         atomic_set(&ctx->io_count, 0);
 502 #if IS_ENABLED(CONFIG_FSCACHE)
 503         ctx->cache = NULL;
 504 #endif
 505         mutex_init(&ctx->wb_lock);
 506         /* ->releasepage() drives zero_point */
 507         if (use_zero_point) {
 508                 ctx->zero_point = ctx->remote_i_size;
 509                 mapping_set_release_always(ctx->inode.i_mapping);
 510         }
 511 }
 512
 513 /**
 514  * netfs_resize_file - Note that a file got resized
 515  * @ctx: The netfs inode being resized
 516  * @new_i_size: The new file size
 517  * @changed_on_server: The change was applied to the server
 518  *
 519  * Inform the netfs lib that a file got resized so that it can adjust its state.
 520  */
 521 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size,
 522                                      bool changed_on_server)
 523 {
 524         if (changed_on_server)
 525                 ctx->remote_i_size = new_i_size;
 526         if (new_i_size < ctx->zero_point)
 527                 ctx->zero_point = new_i_size;
 528 }
 529
 530 /**
 531  * netfs_i_cookie - Get the cache cookie from the inode
 532  * @ctx: The netfs inode to query
 533  *
 534  * Get the caching cookie (if enabled) from the network filesystem's inode.
 535  */
 536 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
 537 {
 538 #if IS_ENABLED(CONFIG_FSCACHE)
 539         return ctx->cache;
 540 #else
 541         return NULL;
 542 #endif
 543 }
 544
 545 /**
 546  * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete
 547  * @inode: The netfs inode to wait on
 548  *
 549  * Wait for outstanding I/O requests of any type to complete.  This is intended
 550  * to be called from inode eviction routines.  This makes sure that any
 551  * resources held by those requests are cleaned up before we let the inode get
 552  * cleaned up.
 553  */
 554 static inline void netfs_wait_for_outstanding_io(struct inode *inode)
 555 {
 556         struct netfs_inode *ictx = netfs_inode(inode);
 557
 558         wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);
 559 }
 560
 561 #endif /* _LINUX_NETFS_H */