diff options
Diffstat (limited to 'include/linux/netfs.h')
| -rw-r--r-- | include/linux/netfs.h | 556 |
1 files changed, 556 insertions, 0 deletions
diff --git a/include/linux/netfs.h b/include/linux/netfs.h new file mode 100644 index 000000000000..065c17385e53 --- /dev/null +++ b/include/linux/netfs.h @@ -0,0 +1,556 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Network filesystem support services. + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * See: + * + * Documentation/filesystems/netfs_library.rst + * + * for a description of the network filesystem interface declared here. + */ + +#ifndef _LINUX_NETFS_H +#define _LINUX_NETFS_H + +#include <linux/workqueue.h> +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/uio.h> +#include <linux/rolling_buffer.h> + +enum netfs_sreq_ref_trace; +typedef struct mempool_s mempool_t; +struct folio_queue; + +/** + * folio_start_private_2 - Start an fscache write on a folio. [DEPRECATED] + * @folio: The folio. + * + * Call this function before writing a folio to a local cache. Starting a + * second write before the first one finishes is not allowed. + * + * Note that this should no longer be used. + */ +static inline void folio_start_private_2(struct folio *folio) +{ + VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio); + folio_get(folio); + folio_set_private_2(folio); +} + +enum netfs_io_source { + NETFS_SOURCE_UNKNOWN, + NETFS_FILL_WITH_ZEROES, + NETFS_DOWNLOAD_FROM_SERVER, + NETFS_READ_FROM_CACHE, + NETFS_INVALID_READ, + NETFS_UPLOAD_TO_SERVER, + NETFS_WRITE_TO_CACHE, +} __mode(byte); + +typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error); + +/* + * Per-inode context. This wraps the VFS inode. + */ +struct netfs_inode { + struct inode inode; /* The VFS inode */ + const struct netfs_request_ops *ops; +#if IS_ENABLED(CONFIG_FSCACHE) + struct fscache_cookie *cache; +#endif + struct mutex wb_lock; /* Writeback serialisation */ + loff_t remote_i_size; /* Size of the remote file */ + loff_t zero_point; /* Size after which we assume there's no data + * on the server */ + atomic_t io_count; /* Number of outstanding reqs */ + unsigned long flags; +#define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */ +#define NETFS_ICTX_UNBUFFERED 1 /* I/O should not use the pagecache */ +#define NETFS_ICTX_MODIFIED_ATTR 3 /* Indicate change in mtime/ctime */ +#define NETFS_ICTX_SINGLE_NO_UPLOAD 4 /* Monolithic payload, cache but no upload */ +}; + +/* + * A netfs group - for instance a ceph snap. This is marked on dirty pages and + * pages marked with a group must be flushed before they can be written under + * the domain of another group. + */ +struct netfs_group { + refcount_t ref; + void (*free)(struct netfs_group *netfs_group); +}; + +/* + * Information about a dirty page (attached only if necessary). + * folio->private + */ +struct netfs_folio { + struct netfs_group *netfs_group; /* Filesystem's grouping marker (or NULL). */ + unsigned int dirty_offset; /* Write-streaming dirty data offset */ + unsigned int dirty_len; /* Write-streaming dirty data length */ +}; +#define NETFS_FOLIO_INFO 0x1UL /* OR'd with folio->private. */ +#define NETFS_FOLIO_COPY_TO_CACHE ((struct netfs_group *)0x356UL) /* Write to the cache only */ + +static inline bool netfs_is_folio_info(const void *priv) +{ + return (unsigned long)priv & NETFS_FOLIO_INFO; +} + +static inline struct netfs_folio *__netfs_folio_info(const void *priv) +{ + if (netfs_is_folio_info(priv)) + return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO); + return NULL; +} + +static inline struct netfs_folio *netfs_folio_info(struct folio *folio) +{ + return __netfs_folio_info(folio_get_private(folio)); +} + +static inline struct netfs_group *netfs_folio_group(struct folio *folio) +{ + struct netfs_folio *finfo; + void *priv = folio_get_private(folio); + + finfo = netfs_folio_info(folio); + if (finfo) + return finfo->netfs_group; + return priv; +} + +/* + * Stream of I/O subrequests going to a particular destination, such as the + * server or the local cache. This is mainly intended for writing where we may + * have to write to multiple destinations concurrently. + */ +struct netfs_io_stream { + /* Submission tracking */ + struct netfs_io_subrequest *construct; /* Op being constructed */ + size_t sreq_max_len; /* Maximum size of a subrequest */ + unsigned int sreq_max_segs; /* 0 or max number of segments in an iterator */ + unsigned int submit_off; /* Folio offset we're submitting from */ + unsigned int submit_len; /* Amount of data left to submit */ + unsigned int submit_extendable_to; /* Amount I/O can be rounded up to */ + void (*prepare_write)(struct netfs_io_subrequest *subreq); + void (*issue_write)(struct netfs_io_subrequest *subreq); + /* Collection tracking */ + struct list_head subrequests; /* Contributory I/O operations */ + struct netfs_io_subrequest *front; /* Op being collected */ + unsigned long long collected_to; /* Position we've collected results to */ + size_t transferred; /* The amount transferred from this stream */ + unsigned short error; /* Aggregate error for the stream */ + enum netfs_io_source source; /* Where to read from/write to */ + unsigned char stream_nr; /* Index of stream in parent table */ + bool avail; /* T if stream is available */ + bool active; /* T if stream is active */ + bool need_retry; /* T if this stream needs retrying */ + bool failed; /* T if this stream failed */ +}; + +/* + * Resources required to do operations on a cache. + */ +struct netfs_cache_resources { + const struct netfs_cache_ops *ops; + void *cache_priv; + void *cache_priv2; + unsigned int debug_id; /* Cookie debug ID */ + unsigned int inval_counter; /* object->inval_counter at begin_op */ +}; + +/* + * Descriptor for a single component subrequest. Each operation represents an + * individual read/write from/to a server, a cache, a journal, etc.. + * + * The buffer iterator is persistent for the life of the subrequest struct and + * the pages it points to can be relied on to exist for the duration. + */ +struct netfs_io_subrequest { + struct netfs_io_request *rreq; /* Supervising I/O request */ + struct work_struct work; + struct list_head rreq_link; /* Link in rreq->subrequests */ + struct iov_iter io_iter; /* Iterator for this subrequest */ + unsigned long long start; /* Where to start the I/O */ + size_t len; /* Size of the I/O */ + size_t transferred; /* Amount of data transferred */ + refcount_t ref; + short error; /* 0 or error that occurred */ + unsigned short debug_index; /* Index in list (for debugging output) */ + unsigned int nr_segs; /* Number of segs in io_iter */ + u8 retry_count; /* The number of retries (0 on initial pass) */ + enum netfs_io_source source; /* Where to read from/write to */ + unsigned char stream_nr; /* I/O stream this belongs to */ + unsigned long flags; +#define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */ +#define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */ +#define NETFS_SREQ_MADE_PROGRESS 4 /* Set if we transferred at least some data */ +#define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */ +#define NETFS_SREQ_BOUNDARY 6 /* Set if ends on hard boundary (eg. ceph object) */ +#define NETFS_SREQ_HIT_EOF 7 /* Set if short due to EOF */ +#define NETFS_SREQ_IN_PROGRESS 8 /* Unlocked when the subrequest completes */ +#define NETFS_SREQ_NEED_RETRY 9 /* Set if the filesystem requests a retry */ +#define NETFS_SREQ_FAILED 10 /* Set if the subreq failed unretryably */ +}; + +enum netfs_io_origin { + NETFS_READAHEAD, /* This read was triggered by readahead */ + NETFS_READPAGE, /* This read is a synchronous read */ + NETFS_READ_GAPS, /* This read is a synchronous read to fill gaps */ + NETFS_READ_SINGLE, /* This read should be treated as a single object */ + NETFS_READ_FOR_WRITE, /* This read is to prepare a write */ + NETFS_UNBUFFERED_READ, /* This is an unbuffered read */ + NETFS_DIO_READ, /* This is a direct I/O read */ + NETFS_WRITEBACK, /* This write was triggered by writepages */ + NETFS_WRITEBACK_SINGLE, /* This monolithic write was triggered by writepages */ + NETFS_WRITETHROUGH, /* This write was made by netfs_perform_write() */ + NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */ + NETFS_DIO_WRITE, /* This is a direct I/O write */ + NETFS_PGPRIV2_COPY_TO_CACHE, /* [DEPRECATED] This is writing read data to the cache */ + nr__netfs_io_origin +} __mode(byte); + +/* + * Descriptor for an I/O helper request. This is used to make multiple I/O + * operations to a variety of data stores and then stitch the result together. + */ +struct netfs_io_request { + union { + struct work_struct cleanup_work; /* Deferred cleanup work */ + struct rcu_head rcu; + }; + struct work_struct work; /* Result collector work */ + struct inode *inode; /* The file being accessed */ + struct address_space *mapping; /* The mapping being accessed */ + struct kiocb *iocb; /* AIO completion vector */ + struct netfs_cache_resources cache_resources; + struct netfs_io_request *copy_to_cache; /* Request to write just-read data to the cache */ +#ifdef CONFIG_PROC_FS + struct list_head proc_link; /* Link in netfs_iorequests */ +#endif + struct netfs_io_stream io_streams[2]; /* Streams of parallel I/O operations */ +#define NR_IO_STREAMS 2 //wreq->nr_io_streams + struct netfs_group *group; /* Writeback group being written back */ + struct rolling_buffer buffer; /* Unencrypted buffer */ +#define NETFS_ROLLBUF_PUT_MARK ROLLBUF_MARK_1 +#define NETFS_ROLLBUF_PAGECACHE_MARK ROLLBUF_MARK_2 + wait_queue_head_t waitq; /* Processor waiter */ + void *netfs_priv; /* Private data for the netfs */ + void *netfs_priv2; /* Private data for the netfs */ + struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */ + unsigned long long submitted; /* Amount submitted for I/O so far */ + unsigned long long len; /* Length of the request */ + size_t transferred; /* Amount to be indicated as transferred */ + long error; /* 0 or error that occurred */ + unsigned long long i_size; /* Size of the file */ + unsigned long long start; /* Start position */ + atomic64_t issued_to; /* Write issuer folio cursor */ + unsigned long long collected_to; /* Point we've collected to */ + unsigned long long cleaned_to; /* Position we've cleaned folios to */ + unsigned long long abandon_to; /* Position to abandon folios to */ + pgoff_t no_unlock_folio; /* Don't unlock this folio after read */ + unsigned int direct_bv_count; /* Number of elements in direct_bv[] */ + unsigned int debug_id; + unsigned int rsize; /* Maximum read size (0 for none) */ + unsigned int wsize; /* Maximum write size (0 for none) */ + atomic_t subreq_counter; /* Next subreq->debug_index */ + unsigned int nr_group_rel; /* Number of refs to release on ->group */ + spinlock_t lock; /* Lock for queuing subreqs */ + unsigned char front_folio_order; /* Order (size) of front folio */ + enum netfs_io_origin origin; /* Origin of the request */ + bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */ + refcount_t ref; + unsigned long flags; +#define NETFS_RREQ_OFFLOAD_COLLECTION 0 /* Offload collection to workqueue */ +#define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */ +#define NETFS_RREQ_FAILED 4 /* The request failed */ +#define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes (has ref) */ +#define NETFS_RREQ_FOLIO_COPY_TO_CACHE 6 /* Copy current folio to cache from read */ +#define NETFS_RREQ_UPLOAD_TO_SERVER 8 /* Need to write to the server */ +#define NETFS_RREQ_PAUSE 11 /* Pause subrequest generation */ +#define NETFS_RREQ_USE_IO_ITER 12 /* Use ->io_iter rather than ->i_pages */ +#define NETFS_RREQ_ALL_QUEUED 13 /* All subreqs are now queued */ +#define NETFS_RREQ_RETRYING 14 /* Set if we're in the retry path */ +#define NETFS_RREQ_SHORT_TRANSFER 15 /* Set if we have a short transfer */ +#define NETFS_RREQ_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark + * write to cache on read */ + const struct netfs_request_ops *netfs_ops; + void (*cleanup)(struct netfs_io_request *req); +}; + +/* + * Operations the network filesystem can/must provide to the helpers. + */ +struct netfs_request_ops { + mempool_t *request_pool; + mempool_t *subrequest_pool; + int (*init_request)(struct netfs_io_request *rreq, struct file *file); + void (*free_request)(struct netfs_io_request *rreq); + void (*free_subrequest)(struct netfs_io_subrequest *rreq); + + /* Read request handling */ + void (*expand_readahead)(struct netfs_io_request *rreq); + int (*prepare_read)(struct netfs_io_subrequest *subreq); + void (*issue_read)(struct netfs_io_subrequest *subreq); + bool (*is_still_valid)(struct netfs_io_request *rreq); + int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, + struct folio **foliop, void **_fsdata); + void (*done)(struct netfs_io_request *rreq); + + /* Modification handling */ + void (*update_i_size)(struct inode *inode, loff_t i_size); + void (*post_modify)(struct inode *inode); + + /* Write request handling */ + void (*begin_writeback)(struct netfs_io_request *wreq); + void (*prepare_write)(struct netfs_io_subrequest *subreq); + void (*issue_write)(struct netfs_io_subrequest *subreq); + void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream); + void (*invalidate_cache)(struct netfs_io_request *wreq); +}; + +/* + * How to handle reading from a hole. + */ +enum netfs_read_from_hole { + NETFS_READ_HOLE_IGNORE, + NETFS_READ_HOLE_FAIL, +}; + +/* + * Table of operations for access to a cache. + */ +struct netfs_cache_ops { + /* End an operation */ + void (*end_operation)(struct netfs_cache_resources *cres); + + /* Read data from the cache */ + int (*read)(struct netfs_cache_resources *cres, + loff_t start_pos, + struct iov_iter *iter, + enum netfs_read_from_hole read_hole, + netfs_io_terminated_t term_func, + void *term_func_priv); + + /* Write data to the cache */ + int (*write)(struct netfs_cache_resources *cres, + loff_t start_pos, + struct iov_iter *iter, + netfs_io_terminated_t term_func, + void *term_func_priv); + + /* Write data to the cache from a netfs subrequest. */ + void (*issue_write)(struct netfs_io_subrequest *subreq); + + /* Expand readahead request */ + void (*expand_readahead)(struct netfs_cache_resources *cres, + unsigned long long *_start, + unsigned long long *_len, + unsigned long long i_size); + + /* Prepare a read operation, shortening it to a cached/uncached + * boundary as appropriate. + */ + enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq, + unsigned long long i_size); + + /* Prepare a write subrequest, working out if we're allowed to do it + * and finding out the maximum amount of data to gather before + * attempting to submit. If we're not permitted to do it, the + * subrequest should be marked failed. + */ + void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq); + + /* Prepare a write operation, working out what part of the write we can + * actually do. + */ + int (*prepare_write)(struct netfs_cache_resources *cres, + loff_t *_start, size_t *_len, size_t upper_len, + loff_t i_size, bool no_space_allocated_yet); + + /* Prepare an on-demand read operation, shortening it to a cached/uncached + * boundary as appropriate. + */ + enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres, + loff_t start, size_t *_len, + loff_t i_size, + unsigned long *_flags, ino_t ino); + + /* Query the occupancy of the cache in a region, returning where the + * next chunk of data starts and how long it is. + */ + int (*query_occupancy)(struct netfs_cache_resources *cres, + loff_t start, size_t len, size_t granularity, + loff_t *_data_start, size_t *_data_len); +}; + +/* High-level read API. */ +ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter); +ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter); +ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter); +ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter); + +/* High-level write API */ +ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter, + struct netfs_group *netfs_group); +ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from, + struct netfs_group *netfs_group); +ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from); +ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter, + struct netfs_group *netfs_group); +ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from); + +/* Single, monolithic object read/write API. */ +void netfs_single_mark_inode_dirty(struct inode *inode); +ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter); +int netfs_writeback_single(struct address_space *mapping, + struct writeback_control *wbc, + struct iov_iter *iter); + +/* Address operations API */ +struct readahead_control; +void netfs_readahead(struct readahead_control *); +int netfs_read_folio(struct file *, struct folio *); +int netfs_write_begin(struct netfs_inode *, struct file *, + struct address_space *, loff_t pos, unsigned int len, + struct folio **, void **fsdata); +int netfs_writepages(struct address_space *mapping, + struct writeback_control *wbc); +bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio); +int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc); +void netfs_clear_inode_writeback(struct inode *inode, const void *aux); +void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length); +bool netfs_release_folio(struct folio *folio, gfp_t gfp); + +/* VMA operations API. */ +vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group); + +/* (Sub)request management API. */ +void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq); +void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq); +void netfs_get_subrequest(struct netfs_io_subrequest *subreq, + enum netfs_sreq_ref_trace what); +void netfs_put_subrequest(struct netfs_io_subrequest *subreq, + enum netfs_sreq_ref_trace what); +ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len, + struct iov_iter *new, + iov_iter_extraction_t extraction_flags); +size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset, + size_t max_size, size_t max_segs); +void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq); +void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error); +void netfs_queue_write_request(struct netfs_io_subrequest *subreq); + +int netfs_start_io_read(struct inode *inode); +void netfs_end_io_read(struct inode *inode); +int netfs_start_io_write(struct inode *inode); +void netfs_end_io_write(struct inode *inode); +int netfs_start_io_direct(struct inode *inode); +void netfs_end_io_direct(struct inode *inode); + +/* Miscellaneous APIs. */ +struct folio_queue *netfs_folioq_alloc(unsigned int rreq_id, gfp_t gfp, + unsigned int trace /*enum netfs_folioq_trace*/); +void netfs_folioq_free(struct folio_queue *folioq, + unsigned int trace /*enum netfs_trace_folioq*/); + +/* Buffer wrangling helpers API. */ +int netfs_alloc_folioq_buffer(struct address_space *mapping, + struct folio_queue **_buffer, + size_t *_cur_size, ssize_t size, gfp_t gfp); +void netfs_free_folioq_buffer(struct folio_queue *fq); + +/** + * netfs_inode - Get the netfs inode context from the inode + * @inode: The inode to query + * + * Get the netfs lib inode context from the network filesystem's inode. The + * context struct is expected to directly follow on from the VFS inode struct. + */ +static inline struct netfs_inode *netfs_inode(struct inode *inode) +{ + return container_of(inode, struct netfs_inode, inode); +} + +/** + * netfs_inode_init - Initialise a netfslib inode context + * @ctx: The netfs inode to initialise + * @ops: The netfs's operations list + * @use_zero_point: True to use the zero_point read optimisation + * + * Initialise the netfs library context struct. This is expected to follow on + * directly from the VFS inode struct. + */ +static inline void netfs_inode_init(struct netfs_inode *ctx, + const struct netfs_request_ops *ops, + bool use_zero_point) +{ + ctx->ops = ops; + ctx->remote_i_size = i_size_read(&ctx->inode); + ctx->zero_point = LLONG_MAX; + ctx->flags = 0; + atomic_set(&ctx->io_count, 0); +#if IS_ENABLED(CONFIG_FSCACHE) + ctx->cache = NULL; +#endif + mutex_init(&ctx->wb_lock); + /* ->releasepage() drives zero_point */ + if (use_zero_point) { + ctx->zero_point = ctx->remote_i_size; + mapping_set_release_always(ctx->inode.i_mapping); + } +} + +/** + * netfs_resize_file - Note that a file got resized + * @ctx: The netfs inode being resized + * @new_i_size: The new file size + * @changed_on_server: The change was applied to the server + * + * Inform the netfs lib that a file got resized so that it can adjust its state. + */ +static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size, + bool changed_on_server) +{ + if (changed_on_server) + ctx->remote_i_size = new_i_size; + if (new_i_size < ctx->zero_point) + ctx->zero_point = new_i_size; +} + +/** + * netfs_i_cookie - Get the cache cookie from the inode + * @ctx: The netfs inode to query + * + * Get the caching cookie (if enabled) from the network filesystem's inode. + */ +static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx) +{ +#if IS_ENABLED(CONFIG_FSCACHE) + return ctx->cache; +#else + return NULL; +#endif +} + +/** + * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete + * @inode: The netfs inode to wait on + * + * Wait for outstanding I/O requests of any type to complete. This is intended + * to be called from inode eviction routines. This makes sure that any + * resources held by those requests are cleaned up before we let the inode get + * cleaned up. + */ +static inline void netfs_wait_for_outstanding_io(struct inode *inode) +{ + struct netfs_inode *ictx = netfs_inode(inode); + + wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0); +} + +#endif /* _LINUX_NETFS_H */ |