linux/fs/afs/file.c
David Howells 3003bbd069 afs: Use the netfs_write_begin() helper
Make AFS use the new netfs_write_begin() helper to do the pre-reading
required before the write.  If successful, the helper returns with the
required page filled in and locked.  It may read more than just one page,
expanding the read to meet cache granularity requirements as necessary.

Note: A more advanced version of this could be made that does
generic_perform_write() for a whole cache granule.  This would make it
easier to avoid doing the download/read for the data to be overwritten.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/160588546422.3465195.1546354372589291098.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161539563244.286939.16537296241609909980.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653819291.2770958.406013201547420544.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789102743.6155.17396591236631761195.stgit@warthog.procyon.org.uk/ # v6
2021-04-23 10:17:28 +01:00

505 lines
12 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/netfs.h>
#include "internal.h"
static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
static int afs_readpage(struct file *file, struct page *page);
static void afs_invalidatepage(struct page *page, unsigned int offset,
unsigned int length);
static int afs_releasepage(struct page *page, gfp_t gfp_flags);
static void afs_readahead(struct readahead_control *ractl);
const struct file_operations afs_file_operations = {
.open = afs_open,
.release = afs_release,
.llseek = generic_file_llseek,
.read_iter = generic_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_fs_aops = {
.readpage = afs_readpage,
.readahead = afs_readahead,
.set_page_dirty = afs_set_page_dirty,
.launder_page = afs_launder_page,
.releasepage = afs_releasepage,
.invalidatepage = afs_invalidatepage,
.write_begin = afs_write_begin,
.write_end = afs_write_end,
.writepage = afs_writepage,
.writepages = afs_writepages,
};
static const struct vm_operations_struct afs_vm_ops = {
.fault = filemap_fault,
.map_pages = filemap_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);
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 *vnode = AFS_FS_I(inode);
struct afs_file *af = file->private_data;
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);
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_read_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_req_issue_op(struct netfs_read_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 = 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);
}
static int afs_symlink_readpage(struct page *page)
{
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
struct afs_read *fsreq;
int ret;
fsreq = afs_alloc_read(GFP_NOFS);
if (!fsreq)
return -ENOMEM;
fsreq->pos = page->index * PAGE_SIZE;
fsreq->len = PAGE_SIZE;
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);
page_endio(page, false, ret);
return ret;
}
static void afs_init_rreq(struct netfs_read_request *rreq, struct file *file)
{
rreq->netfs_priv = key_get(afs_file_key(file));
}
static bool afs_is_cache_enabled(struct inode *inode)
{
struct fscache_cookie *cookie = afs_vnode_cache(AFS_FS_I(inode));
return fscache_cookie_enabled(cookie) && !hlist_empty(&cookie->backing_objects);
}
static int afs_begin_cache_operation(struct netfs_read_request *rreq)
{
struct afs_vnode *vnode = AFS_FS_I(rreq->inode);
return fscache_begin_read_operation(rreq, afs_vnode_cache(vnode));
}
static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
struct page *page, 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_read_request_ops afs_req_ops = {
.init_rreq = afs_init_rreq,
.is_cache_enabled = afs_is_cache_enabled,
.begin_cache_operation = afs_begin_cache_operation,
.check_write_begin = afs_check_write_begin,
.issue_op = afs_req_issue_op,
.cleanup = afs_priv_cleanup,
};
static int afs_readpage(struct file *file, struct page *page)
{
if (!file)
return afs_symlink_readpage(page);
return netfs_readpage(file, page, &afs_req_ops, NULL);
}
static void afs_readahead(struct readahead_control *ractl)
{
netfs_readahead(ractl, &afs_req_ops, NULL);
}
/*
* 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 page *page, unsigned int offset,
unsigned int length)
{
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
unsigned long priv;
unsigned int f, t, end = offset + length;
priv = page_private(page);
/* we clean up only if the entire page is being invalidated */
if (offset == 0 && length == thp_size(page))
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_page_dirty_mmapped(priv))
return;
/* We may need to shorten the dirty region */
f = afs_page_dirty_from(page, priv);
t = afs_page_dirty_to(page, 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_page_dirty(page, f, t);
set_page_private(page, priv);
trace_afs_page_dirty(vnode, tracepoint_string("trunc"), page);
return;
undirty:
trace_afs_page_dirty(vnode, tracepoint_string("undirty"), page);
clear_page_dirty_for_io(page);
full_invalidate:
trace_afs_page_dirty(vnode, tracepoint_string("inval"), page);
detach_page_private(page);
}
/*
* 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_invalidatepage(struct page *page, unsigned int offset,
unsigned int length)
{
_enter("{%lu},%u,%u", page->index, offset, length);
BUG_ON(!PageLocked(page));
if (PagePrivate(page))
afs_invalidate_dirty(page, offset, length);
wait_on_page_fscache(page);
_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_flags)
{
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
_enter("{{%llx:%llu}[%lu],%lx},%x",
vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
gfp_flags);
/* deny if page is being written to the cache and the caller hasn't
* elected to wait */
#ifdef CONFIG_AFS_FSCACHE
if (PageFsCache(page)) {
if (!(gfp_flags & __GFP_DIRECT_RECLAIM) || !(gfp_flags & __GFP_FS))
return false;
wait_on_page_fscache(page);
}
#endif
if (PagePrivate(page)) {
trace_afs_page_dirty(vnode, tracepoint_string("rel"), page);
detach_page_private(page);
}
/* indicate that the page can be released */
_leave(" = T");
return 1;
}
/*
* Handle setting up a memory mapping on an AFS file.
*/
static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
int ret;
ret = generic_file_mmap(file, vma);
if (ret == 0)
vma->vm_ops = &afs_vm_ops;
return ret;
}