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/* 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 ([email protected])
*
* 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>
enum netfs_sreq_ref_trace;
/*
* Overload PG_private_2 to give us PG_fscache - this is used to indicate that
* a page is currently backed by a local disk cache
*/
#define folio_test_fscache(folio) folio_test_private_2(folio)
#define PageFsCache(page) PagePrivate2((page))
#define SetPageFsCache(page) SetPagePrivate2((page))
#define ClearPageFsCache(page) ClearPagePrivate2((page))
#define TestSetPageFsCache(page) TestSetPagePrivate2((page))
#define TestClearPageFsCache(page) TestClearPagePrivate2((page))
/**
* folio_start_fscache - Start an fscache write on a folio.
* @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.
*/
static inline void folio_start_fscache(struct folio *folio)
{
VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
folio_get(folio);
folio_set_private_2(folio);
}
/**
* folio_end_fscache - End an fscache write on a folio.
* @folio: The folio.
*
* Call this function after the folio has been written to the local cache.
* This will wake any sleepers waiting on this folio.
*/
static inline void folio_end_fscache(struct folio *folio)
{
folio_end_private_2(folio);
}
/**
* folio_wait_fscache - Wait for an fscache write on this folio to end.
* @folio: The folio.
*
* If this folio is currently being written to a local cache, wait for
* the write to finish. Another write may start after this one finishes,
* unless the caller holds the folio lock.
*/
static inline void folio_wait_fscache(struct folio *folio)
{
folio_wait_private_2(folio);
}
/**
* folio_wait_fscache_killable - Wait for an fscache write on this folio to end.
* @folio: The folio.
*
* If this folio is currently being written to a local cache, wait
* for the write to finish or for a fatal signal to be received.
* Another write may start after this one finishes, unless the caller
* holds the folio lock.
*
* Return:
* - 0 if successful.
* - -EINTR if a fatal signal was encountered.
*/
static inline int folio_wait_fscache_killable(struct folio *folio)
{
return folio_wait_private_2_killable(folio);
}
static inline void set_page_fscache(struct page *page)
{
folio_start_fscache(page_folio(page));
}
static inline void end_page_fscache(struct page *page)
{
folio_end_private_2(page_folio(page));
}
static inline void wait_on_page_fscache(struct page *page)
{
folio_wait_private_2(page_folio(page));
}
static inline int wait_on_page_fscache_killable(struct page *page)
{
return folio_wait_private_2_killable(page_folio(page));
}
/* Marks used on xarray-based buffers */
#define NETFS_BUF_PUT_MARK XA_MARK_0 /* - Page needs putting */
#define NETFS_BUF_PAGECACHE_MARK XA_MARK_1 /* - Page needs wb/dirty flag wrangling */
enum netfs_io_source {
NETFS_FILL_WITH_ZEROES,
NETFS_DOWNLOAD_FROM_SERVER,
NETFS_READ_FROM_CACHE,
NETFS_INVALID_READ,
NETFS_UPLOAD_TO_SERVER,
NETFS_WRITE_TO_CACHE,
NETFS_INVALID_WRITE,
} __mode(byte);
typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
bool was_async);
/*
* 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
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 */
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_WRITETHROUGH 2 /* Write-through caching */
#define NETFS_ICTX_NO_WRITE_STREAMING 3 /* Don't engage in write-streaming */
};
/*
* 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. */
static inline struct netfs_folio *netfs_folio_info(struct folio *folio)
{
void *priv = folio_get_private(folio);
if ((unsigned long)priv & NETFS_FOLIO_INFO)
return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO);
return NULL;
}
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;
}
/*
* 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 */
loff_t 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 max_nr_segs; /* 0 or max number of segments in an iterator */
enum netfs_io_source source; /* Where to read from/write 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_SHORT_IO 2 /* Set if the I/O was short */
#define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */
#define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */
#define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */
};
enum netfs_io_origin {
NETFS_READAHEAD, /* This read was triggered by readahead */
NETFS_READPAGE, /* This read is a synchronous read */
NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
NETFS_WRITEBACK, /* This write was triggered by writepages */
NETFS_WRITETHROUGH, /* This write was made by netfs_perform_write() */
NETFS_LAUNDER_WRITE, /* This is triggered by ->launder_folio() */
NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */
NETFS_DIO_READ, /* This is a direct I/O read */
NETFS_DIO_WRITE, /* This is a direct I/O write */
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 work;
struct rcu_head rcu;
};
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 list_head proc_link; /* Link in netfs_iorequests */
struct list_head subrequests; /* Contributory I/O operations */
struct iov_iter iter; /* Unencrypted-side iterator */
struct iov_iter io_iter; /* I/O (Encrypted-side) iterator */
void *netfs_priv; /* Private data for the netfs */
struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */
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) */
unsigned int subreq_counter; /* Next subreq->debug_index */
atomic_t nr_outstanding; /* Number of ops in progress */
atomic_t nr_copy_ops; /* Number of copy-to-cache ops in progress */
size_t submitted; /* Amount submitted for I/O so far */
size_t len; /* Length of the request */
size_t upper_len; /* Length can be extended to here */
size_t transferred; /* Amount to be indicated as transferred */
short error; /* 0 or error that occurred */
enum netfs_io_origin origin; /* Origin of the request */
bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */
loff_t i_size; /* Size of the file */
loff_t start; /* Start position */
pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
refcount_t ref;
unsigned long flags;
#define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */
#define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */
#define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */
#define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */
#define NETFS_RREQ_FAILED 4 /* The request failed */
#define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */
#define NETFS_RREQ_WRITE_TO_CACHE 7 /* Need to write to the cache */
#define NETFS_RREQ_UPLOAD_TO_SERVER 8 /* Need to write to the server */
#define NETFS_RREQ_NONBLOCK 9 /* Don't block if possible (O_NONBLOCK) */
#define NETFS_RREQ_BLOCKED 10 /* We blocked */
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 {
unsigned int io_request_size; /* Alloc size for netfs_io_request struct */
unsigned int io_subrequest_size; /* Alloc size for netfs_io_subrequest struct */
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);
bool (*clamp_length)(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);
/* Write request handling */
void (*create_write_requests)(struct netfs_io_request *wreq,
loff_t start, size_t len);
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_CLEAR,
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);
/* Expand readahead request */
void (*expand_readahead)(struct netfs_cache_resources *cres,
loff_t *_start, size_t *_len, loff_t 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,
loff_t i_size);
/* 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(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_file_write_iter(struct kiocb *iocb, struct iov_iter *from);
/* 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);
int netfs_launder_folio(struct folio *folio);
/* VMA operations API. */
vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
/* (Sub)request management API. */
void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool);
void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
enum netfs_sreq_ref_trace what);
void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
bool was_async, 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);
struct netfs_io_subrequest *netfs_create_write_request(
struct netfs_io_request *wreq, enum netfs_io_source dest,
loff_t start, size_t len, work_func_t worker);
void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
bool was_async);
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);
/**
* 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;
#if IS_ENABLED(CONFIG_FSCACHE)
ctx->cache = NULL;
#endif
/* ->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
}
#endif /* _LINUX_NETFS_H */
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