linux/fs/afs/file.c
Linus Torvalds f008b1d6e1 Netfs prep for write helpers
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Merge tag 'netfs-prep-20220318' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull netfs updates from David Howells:
 "Netfs prep for write helpers.

  Having had a go at implementing write helpers and content encryption
  support in netfslib, it seems that the netfs_read_{,sub}request
  structs and the equivalent write request structs were almost the same
  and so should be merged, thereby requiring only one set of
  alloc/get/put functions and a common set of tracepoints.

  Merging the structs also has the advantage that if a bounce buffer is
  added to the request struct, a read operation can be performed to fill
  the bounce buffer, the contents of the buffer can be modified and then
  a write operation can be performed on it to send the data wherever it
  needs to go using the same request structure all the way through. The
  I/O handlers would then transparently perform any required crypto.
  This should make it easier to perform RMW cycles if needed.

  The potentially common functions and structs, however, by their names
  all proclaim themselves to be associated with the read side of things.

  The bulk of these changes alter this in the following ways:

   - Rename struct netfs_read_{,sub}request to netfs_io_{,sub}request.

   - Rename some enums, members and flags to make them more appropriate.

   - Adjust some comments to match.

   - Drop "read"/"rreq" from the names of common functions. For
     instance, netfs_get_read_request() becomes netfs_get_request().

   - The ->init_rreq() and ->issue_op() methods become ->init_request()
     and ->issue_read(). I've kept the latter as a read-specific
     function and in another branch added an ->issue_write() method.

  The driver source is then reorganised into a number of files:

        fs/netfs/buffered_read.c        Create read reqs to the pagecache
        fs/netfs/io.c                   Dispatchers for read and write reqs
        fs/netfs/main.c                 Some general miscellaneous bits
        fs/netfs/objects.c              Alloc, get and put functions
        fs/netfs/stats.c                Optional procfs statistics.

  and future development can be fitted into this scheme, e.g.:

        fs/netfs/buffered_write.c       Modify the pagecache
        fs/netfs/buffered_flush.c       Writeback from the pagecache
        fs/netfs/direct_read.c          DIO read support
        fs/netfs/direct_write.c         DIO write support
        fs/netfs/unbuffered_write.c     Write modifications directly back

  Beyond the above changes, there are also some changes that affect how
  things work:

   - Make fscache_end_operation() generally available.

   - In the netfs tracing header, generate enums from the symbol ->
     string mapping tables rather than manually coding them.

   - Add a struct for filesystems that uses netfslib to put into their
     inode wrapper structs to hold extra state that netfslib is
     interested in, such as the fscache cookie. This allows netfslib
     functions to be set in filesystem operation tables and jumped to
     directly without having to have a filesystem wrapper.

   - Add a member to the struct added above to track the remote inode
     length as that may differ if local modifications are buffered. We
     may need to supply an appropriate EOF pointer when storing data (in
     AFS for example).

   - Pass extra information to netfs_alloc_request() so that the
     ->init_request() hook can access it and retain information to
     indicate the origin of the operation.

   - Make the ->init_request() hook return an error, thereby allowing a
     filesystem that isn't allowed to cache an inode (ceph or cifs, for
     example) to skip readahead.

   - Switch to using refcount_t for subrequests and add tracepoints to
     log refcount changes for the request and subrequest structs.

   - Add a function to consolidate dispatching a read request. Similar
     code is used in three places and another couple are likely to be
     added in the future"

Link: https://lore.kernel.org/all/2639515.1648483225@warthog.procyon.org.uk/

* tag 'netfs-prep-20220318' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  afs: Maintain netfs_i_context::remote_i_size
  netfs: Keep track of the actual remote file size
  netfs: Split some core bits out into their own file
  netfs: Split fs/netfs/read_helper.c
  netfs: Rename read_helper.c to io.c
  netfs: Prepare to split read_helper.c
  netfs: Add a function to consolidate beginning a read
  netfs: Add a netfs inode context
  ceph: Make ceph_init_request() check caps on readahead
  netfs: Change ->init_request() to return an error code
  netfs: Refactor arguments for netfs_alloc_read_request
  netfs: Adjust the netfs_failure tracepoint to indicate non-subreq lines
  netfs: Trace refcounting on the netfs_io_subrequest struct
  netfs: Trace refcounting on the netfs_io_request struct
  netfs: Adjust the netfs_rreq tracepoint slightly
  netfs: Split netfs_io_* object handling out
  netfs: Finish off rename of netfs_read_request to netfs_io_request
  netfs: Rename netfs_read_*request to netfs_io_*request
  netfs: Generate enums from trace symbol mapping lists
  fscache: export fscache_end_operation()
2022-03-31 15:49:36 -07:00

601 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS filesystem file handling
*
* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/gfp.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/netfs.h>
#include "internal.h"
static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
static int afs_symlink_readpage(struct file *file, struct page *page);
static void afs_invalidate_folio(struct folio *folio, size_t offset,
size_t length);
static int afs_releasepage(struct page *page, gfp_t gfp_flags);
static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
static void afs_vm_open(struct vm_area_struct *area);
static void afs_vm_close(struct vm_area_struct *area);
static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff);
const struct file_operations afs_file_operations = {
.open = afs_open,
.release = afs_release,
.llseek = generic_file_llseek,
.read_iter = afs_file_read_iter,
.write_iter = afs_file_write,
.mmap = afs_file_mmap,
.splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.fsync = afs_fsync,
.lock = afs_lock,
.flock = afs_flock,
};
const struct inode_operations afs_file_inode_operations = {
.getattr = afs_getattr,
.setattr = afs_setattr,
.permission = afs_permission,
};
const struct address_space_operations afs_file_aops = {
.readpage = netfs_readpage,
.readahead = netfs_readahead,
.dirty_folio = afs_dirty_folio,
.launder_folio = afs_launder_folio,
.releasepage = afs_releasepage,
.invalidate_folio = afs_invalidate_folio,
.write_begin = afs_write_begin,
.write_end = afs_write_end,
.writepage = afs_writepage,
.writepages = afs_writepages,
};
const struct address_space_operations afs_symlink_aops = {
.readpage = afs_symlink_readpage,
.releasepage = afs_releasepage,
.invalidate_folio = afs_invalidate_folio,
};
static const struct vm_operations_struct afs_vm_ops = {
.open = afs_vm_open,
.close = afs_vm_close,
.fault = filemap_fault,
.map_pages = afs_vm_map_pages,
.page_mkwrite = afs_page_mkwrite,
};
/*
* Discard a pin on a writeback key.
*/
void afs_put_wb_key(struct afs_wb_key *wbk)
{
if (wbk && refcount_dec_and_test(&wbk->usage)) {
key_put(wbk->key);
kfree(wbk);
}
}
/*
* Cache key for writeback.
*/
int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
{
struct afs_wb_key *wbk, *p;
wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
if (!wbk)
return -ENOMEM;
refcount_set(&wbk->usage, 2);
wbk->key = af->key;
spin_lock(&vnode->wb_lock);
list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
if (p->key == wbk->key)
goto found;
}
key_get(wbk->key);
list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
spin_unlock(&vnode->wb_lock);
af->wb = wbk;
return 0;
found:
refcount_inc(&p->usage);
spin_unlock(&vnode->wb_lock);
af->wb = p;
kfree(wbk);
return 0;
}
/*
* open an AFS file or directory and attach a key to it
*/
int afs_open(struct inode *inode, struct file *file)
{
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_file *af;
struct key *key;
int ret;
_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
goto error;
}
af = kzalloc(sizeof(*af), GFP_KERNEL);
if (!af) {
ret = -ENOMEM;
goto error_key;
}
af->key = key;
ret = afs_validate(vnode, key);
if (ret < 0)
goto error_af;
if (file->f_mode & FMODE_WRITE) {
ret = afs_cache_wb_key(vnode, af);
if (ret < 0)
goto error_af;
}
if (file->f_flags & O_TRUNC)
set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
fscache_use_cookie(afs_vnode_cache(vnode), file->f_mode & FMODE_WRITE);
file->private_data = af;
_leave(" = 0");
return 0;
error_af:
kfree(af);
error_key:
key_put(key);
error:
_leave(" = %d", ret);
return ret;
}
/*
* release an AFS file or directory and discard its key
*/
int afs_release(struct inode *inode, struct file *file)
{
struct afs_vnode_cache_aux aux;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_file *af = file->private_data;
loff_t i_size;
int ret = 0;
_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
if ((file->f_mode & FMODE_WRITE))
ret = vfs_fsync(file, 0);
file->private_data = NULL;
if (af->wb)
afs_put_wb_key(af->wb);
if ((file->f_mode & FMODE_WRITE)) {
i_size = i_size_read(&vnode->vfs_inode);
afs_set_cache_aux(vnode, &aux);
fscache_unuse_cookie(afs_vnode_cache(vnode), &aux, &i_size);
} else {
fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL);
}
key_put(af->key);
kfree(af);
afs_prune_wb_keys(vnode);
_leave(" = %d", ret);
return ret;
}
/*
* Allocate a new read record.
*/
struct afs_read *afs_alloc_read(gfp_t gfp)
{
struct afs_read *req;
req = kzalloc(sizeof(struct afs_read), gfp);
if (req)
refcount_set(&req->usage, 1);
return req;
}
/*
* Dispose of a ref to a read record.
*/
void afs_put_read(struct afs_read *req)
{
if (refcount_dec_and_test(&req->usage)) {
if (req->cleanup)
req->cleanup(req);
key_put(req->key);
kfree(req);
}
}
static void afs_fetch_data_notify(struct afs_operation *op)
{
struct afs_read *req = op->fetch.req;
struct netfs_io_subrequest *subreq = req->subreq;
int error = op->error;
if (error == -ECONNABORTED)
error = afs_abort_to_error(op->ac.abort_code);
req->error = error;
if (subreq) {
__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
netfs_subreq_terminated(subreq, error ?: req->actual_len, false);
req->subreq = NULL;
} else if (req->done) {
req->done(req);
}
}
static void afs_fetch_data_success(struct afs_operation *op)
{
struct afs_vnode *vnode = op->file[0].vnode;
_enter("op=%08x", op->debug_id);
afs_vnode_commit_status(op, &op->file[0]);
afs_stat_v(vnode, n_fetches);
atomic_long_add(op->fetch.req->actual_len, &op->net->n_fetch_bytes);
afs_fetch_data_notify(op);
}
static void afs_fetch_data_put(struct afs_operation *op)
{
op->fetch.req->error = op->error;
afs_put_read(op->fetch.req);
}
static const struct afs_operation_ops afs_fetch_data_operation = {
.issue_afs_rpc = afs_fs_fetch_data,
.issue_yfs_rpc = yfs_fs_fetch_data,
.success = afs_fetch_data_success,
.aborted = afs_check_for_remote_deletion,
.failed = afs_fetch_data_notify,
.put = afs_fetch_data_put,
};
/*
* Fetch file data from the volume.
*/
int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
{
struct afs_operation *op;
_enter("%s{%llx:%llu.%u},%x,,,",
vnode->volume->name,
vnode->fid.vid,
vnode->fid.vnode,
vnode->fid.unique,
key_serial(req->key));
op = afs_alloc_operation(req->key, vnode->volume);
if (IS_ERR(op)) {
if (req->subreq)
netfs_subreq_terminated(req->subreq, PTR_ERR(op), false);
return PTR_ERR(op);
}
afs_op_set_vnode(op, 0, vnode);
op->fetch.req = afs_get_read(req);
op->ops = &afs_fetch_data_operation;
return afs_do_sync_operation(op);
}
static void afs_issue_read(struct netfs_io_subrequest *subreq)
{
struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
struct afs_read *fsreq;
fsreq = afs_alloc_read(GFP_NOFS);
if (!fsreq)
return netfs_subreq_terminated(subreq, -ENOMEM, false);
fsreq->subreq = subreq;
fsreq->pos = subreq->start + subreq->transferred;
fsreq->len = subreq->len - subreq->transferred;
fsreq->key = key_get(subreq->rreq->netfs_priv);
fsreq->vnode = vnode;
fsreq->iter = &fsreq->def_iter;
iov_iter_xarray(&fsreq->def_iter, READ,
&fsreq->vnode->vfs_inode.i_mapping->i_pages,
fsreq->pos, fsreq->len);
afs_fetch_data(fsreq->vnode, fsreq);
afs_put_read(fsreq);
}
static int afs_symlink_readpage(struct file *file, struct page *page)
{
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
struct afs_read *fsreq;
struct folio *folio = page_folio(page);
int ret;
fsreq = afs_alloc_read(GFP_NOFS);
if (!fsreq)
return -ENOMEM;
fsreq->pos = folio_pos(folio);
fsreq->len = folio_size(folio);
fsreq->vnode = vnode;
fsreq->iter = &fsreq->def_iter;
iov_iter_xarray(&fsreq->def_iter, READ, &page->mapping->i_pages,
fsreq->pos, fsreq->len);
ret = afs_fetch_data(fsreq->vnode, fsreq);
if (ret == 0)
SetPageUptodate(page);
unlock_page(page);
return ret;
}
static int afs_init_request(struct netfs_io_request *rreq, struct file *file)
{
rreq->netfs_priv = key_get(afs_file_key(file));
return 0;
}
static int afs_begin_cache_operation(struct netfs_io_request *rreq)
{
#ifdef CONFIG_AFS_FSCACHE
struct afs_vnode *vnode = AFS_FS_I(rreq->inode);
return fscache_begin_read_operation(&rreq->cache_resources,
afs_vnode_cache(vnode));
#else
return -ENOBUFS;
#endif
}
static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
struct folio *folio, void **_fsdata)
{
struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
return test_bit(AFS_VNODE_DELETED, &vnode->flags) ? -ESTALE : 0;
}
static void afs_priv_cleanup(struct address_space *mapping, void *netfs_priv)
{
key_put(netfs_priv);
}
const struct netfs_request_ops afs_req_ops = {
.init_request = afs_init_request,
.begin_cache_operation = afs_begin_cache_operation,
.check_write_begin = afs_check_write_begin,
.issue_read = afs_issue_read,
.cleanup = afs_priv_cleanup,
};
int afs_write_inode(struct inode *inode, struct writeback_control *wbc)
{
fscache_unpin_writeback(wbc, afs_vnode_cache(AFS_FS_I(inode)));
return 0;
}
/*
* Adjust the dirty region of the page on truncation or full invalidation,
* getting rid of the markers altogether if the region is entirely invalidated.
*/
static void afs_invalidate_dirty(struct folio *folio, size_t offset,
size_t length)
{
struct afs_vnode *vnode = AFS_FS_I(folio_inode(folio));
unsigned long priv;
unsigned int f, t, end = offset + length;
priv = (unsigned long)folio_get_private(folio);
/* we clean up only if the entire page is being invalidated */
if (offset == 0 && length == folio_size(folio))
goto full_invalidate;
/* If the page was dirtied by page_mkwrite(), the PTE stays writable
* and we don't get another notification to tell us to expand it
* again.
*/
if (afs_is_folio_dirty_mmapped(priv))
return;
/* We may need to shorten the dirty region */
f = afs_folio_dirty_from(folio, priv);
t = afs_folio_dirty_to(folio, priv);
if (t <= offset || f >= end)
return; /* Doesn't overlap */
if (f < offset && t > end)
return; /* Splits the dirty region - just absorb it */
if (f >= offset && t <= end)
goto undirty;
if (f < offset)
t = offset;
else
f = end;
if (f == t)
goto undirty;
priv = afs_folio_dirty(folio, f, t);
folio_change_private(folio, (void *)priv);
trace_afs_folio_dirty(vnode, tracepoint_string("trunc"), folio);
return;
undirty:
trace_afs_folio_dirty(vnode, tracepoint_string("undirty"), folio);
folio_clear_dirty_for_io(folio);
full_invalidate:
trace_afs_folio_dirty(vnode, tracepoint_string("inval"), folio);
folio_detach_private(folio);
}
/*
* invalidate part or all of a page
* - release a page and clean up its private data if offset is 0 (indicating
* the entire page)
*/
static void afs_invalidate_folio(struct folio *folio, size_t offset,
size_t length)
{
_enter("{%lu},%zu,%zu", folio->index, offset, length);
BUG_ON(!folio_test_locked(folio));
if (folio_get_private(folio))
afs_invalidate_dirty(folio, offset, length);
folio_wait_fscache(folio);
_leave("");
}
/*
* release a page and clean up its private state if it's not busy
* - return true if the page can now be released, false if not
*/
static int afs_releasepage(struct page *page, gfp_t gfp)
{
struct folio *folio = page_folio(page);
struct afs_vnode *vnode = AFS_FS_I(folio_inode(folio));
_enter("{{%llx:%llu}[%lu],%lx},%x",
vnode->fid.vid, vnode->fid.vnode, folio_index(folio), folio->flags,
gfp);
/* deny if page is being written to the cache and the caller hasn't
* elected to wait */
#ifdef CONFIG_AFS_FSCACHE
if (folio_test_fscache(folio)) {
if (current_is_kswapd() || !(gfp & __GFP_FS))
return false;
folio_wait_fscache(folio);
}
fscache_note_page_release(afs_vnode_cache(vnode));
#endif
if (folio_test_private(folio)) {
trace_afs_folio_dirty(vnode, tracepoint_string("rel"), folio);
folio_detach_private(folio);
}
/* Indicate that the folio can be released */
_leave(" = T");
return true;
}
static void afs_add_open_mmap(struct afs_vnode *vnode)
{
if (atomic_inc_return(&vnode->cb_nr_mmap) == 1) {
down_write(&vnode->volume->cell->fs_open_mmaps_lock);
if (list_empty(&vnode->cb_mmap_link))
list_add_tail(&vnode->cb_mmap_link,
&vnode->volume->cell->fs_open_mmaps);
up_write(&vnode->volume->cell->fs_open_mmaps_lock);
}
}
static void afs_drop_open_mmap(struct afs_vnode *vnode)
{
if (!atomic_dec_and_test(&vnode->cb_nr_mmap))
return;
down_write(&vnode->volume->cell->fs_open_mmaps_lock);
if (atomic_read(&vnode->cb_nr_mmap) == 0)
list_del_init(&vnode->cb_mmap_link);
up_write(&vnode->volume->cell->fs_open_mmaps_lock);
flush_work(&vnode->cb_work);
}
/*
* Handle setting up a memory mapping on an AFS file.
*/
static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
int ret;
afs_add_open_mmap(vnode);
ret = generic_file_mmap(file, vma);
if (ret == 0)
vma->vm_ops = &afs_vm_ops;
else
afs_drop_open_mmap(vnode);
return ret;
}
static void afs_vm_open(struct vm_area_struct *vma)
{
afs_add_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
}
static void afs_vm_close(struct vm_area_struct *vma)
{
afs_drop_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
}
static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff)
{
struct afs_vnode *vnode = AFS_FS_I(file_inode(vmf->vma->vm_file));
struct afs_file *af = vmf->vma->vm_file->private_data;
switch (afs_validate(vnode, af->key)) {
case 0:
return filemap_map_pages(vmf, start_pgoff, end_pgoff);
case -ENOMEM:
return VM_FAULT_OOM;
case -EINTR:
case -ERESTARTSYS:
return VM_FAULT_RETRY;
case -ESTALE:
default:
return VM_FAULT_SIGBUS;
}
}
static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
struct afs_file *af = iocb->ki_filp->private_data;
int ret;
ret = afs_validate(vnode, af->key);
if (ret < 0)
return ret;
return generic_file_read_iter(iocb, iter);
}