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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-25 21:54:06 +08:00
linux-next/fs/afs/file.c
David Howells f3ddee8dc4 afs: Fix directory handling
AFS directories are structured blobs that are downloaded just like files
and then parsed by the lookup and readdir code and, as such, are currently
handled in the pagecache like any other file, with the entire directory
content being thrown away each time the directory changes.

However, since the blob is a known structure and since the data version
counter on a directory increases by exactly one for each change committed
to that directory, we can actually edit the directory locally rather than
fetching it from the server after each locally-induced change.

What we can't do, though, is mix data from the server and data from the
client since the server is technically at liberty to rearrange or compress
a directory if it sees fit, provided it updates the data version number
when it does so and breaks the callback (ie. sends a notification).

Further, lookup with lookup-ahead, readdir and, when it arrives, local
editing are likely want to scan the whole of a directory.

So directory handling needs to be improved to maintain the coherency of the
directory blob prior to permitting local directory editing.

To this end:

 (1) If any directory page gets discarded, invalidate and reread the entire
     directory.

 (2) If readpage notes that if when it fetches a single page that the
     version number has changed, the entire directory is flagged for
     invalidation.

 (3) Read as much of the directory in one go as we can.

Note that this removes local caching of directories in fscache for the
moment as we can't pass the pages to fscache_read_or_alloc_pages() since
page->lru is in use by the LRU.

Signed-off-by: David Howells <dhowells@redhat.com>
2018-04-09 21:54:48 +01:00

664 lines
15 KiB
C

/* AFS filesystem file handling
*
* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#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 "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 int afs_readpages(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
const struct file_operations afs_file_operations = {
.open = afs_open,
.flush = afs_flush,
.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,
.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,
.listxattr = afs_listxattr,
};
const struct address_space_operations afs_fs_aops = {
.readpage = afs_readpage,
.readpages = afs_readpages,
.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 (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("{%x:%u},", 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;
}
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;
_enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
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(" = 0");
return 0;
}
/*
* Dispose of a ref to a read record.
*/
void afs_put_read(struct afs_read *req)
{
int i;
if (refcount_dec_and_test(&req->usage)) {
for (i = 0; i < req->nr_pages; i++)
if (req->pages[i])
put_page(req->pages[i]);
if (req->pages != req->array)
kfree(req->pages);
kfree(req);
}
}
#ifdef CONFIG_AFS_FSCACHE
/*
* deal with notification that a page was read from the cache
*/
static void afs_file_readpage_read_complete(struct page *page,
void *data,
int error)
{
_enter("%p,%p,%d", page, data, error);
/* if the read completes with an error, we just unlock the page and let
* the VM reissue the readpage */
if (!error)
SetPageUptodate(page);
unlock_page(page);
}
#endif
/*
* Fetch file data from the volume.
*/
int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *desc)
{
struct afs_fs_cursor fc;
int ret;
_enter("%s{%x:%u.%u},%x,,,",
vnode->volume->name,
vnode->fid.vid,
vnode->fid.vnode,
vnode->fid.unique,
key_serial(key));
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, vnode, key)) {
while (afs_select_fileserver(&fc)) {
fc.cb_break = vnode->cb_break + vnode->cb_s_break;
afs_fs_fetch_data(&fc, desc);
}
afs_check_for_remote_deletion(&fc, fc.vnode);
afs_vnode_commit_status(&fc, vnode, fc.cb_break);
ret = afs_end_vnode_operation(&fc);
}
_leave(" = %d", ret);
return ret;
}
/*
* read page from file, directory or symlink, given a key to use
*/
int afs_page_filler(void *data, struct page *page)
{
struct inode *inode = page->mapping->host;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_read *req;
struct key *key = data;
int ret;
_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
BUG_ON(!PageLocked(page));
ret = -ESTALE;
if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
goto error;
/* is it cached? */
#ifdef CONFIG_AFS_FSCACHE
ret = fscache_read_or_alloc_page(vnode->cache,
page,
afs_file_readpage_read_complete,
NULL,
GFP_KERNEL);
#else
ret = -ENOBUFS;
#endif
switch (ret) {
/* read BIO submitted (page in cache) */
case 0:
break;
/* page not yet cached */
case -ENODATA:
_debug("cache said ENODATA");
goto go_on;
/* page will not be cached */
case -ENOBUFS:
_debug("cache said ENOBUFS");
default:
go_on:
req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
GFP_KERNEL);
if (!req)
goto enomem;
/* We request a full page. If the page is a partial one at the
* end of the file, the server will return a short read and the
* unmarshalling code will clear the unfilled space.
*/
refcount_set(&req->usage, 1);
req->pos = (loff_t)page->index << PAGE_SHIFT;
req->len = PAGE_SIZE;
req->nr_pages = 1;
req->pages = req->array;
req->pages[0] = page;
get_page(page);
/* read the contents of the file from the server into the
* page */
ret = afs_fetch_data(vnode, key, req);
afs_put_read(req);
if (ret < 0) {
if (ret == -ENOENT) {
_debug("got NOENT from server"
" - marking file deleted and stale");
set_bit(AFS_VNODE_DELETED, &vnode->flags);
ret = -ESTALE;
}
#ifdef CONFIG_AFS_FSCACHE
fscache_uncache_page(vnode->cache, page);
#endif
BUG_ON(PageFsCache(page));
if (ret == -EINTR ||
ret == -ENOMEM ||
ret == -ERESTARTSYS ||
ret == -EAGAIN)
goto error;
goto io_error;
}
SetPageUptodate(page);
/* send the page to the cache */
#ifdef CONFIG_AFS_FSCACHE
if (PageFsCache(page) &&
fscache_write_page(vnode->cache, page, vnode->status.size,
GFP_KERNEL) != 0) {
fscache_uncache_page(vnode->cache, page);
BUG_ON(PageFsCache(page));
}
#endif
unlock_page(page);
}
_leave(" = 0");
return 0;
io_error:
SetPageError(page);
goto error;
enomem:
ret = -ENOMEM;
error:
unlock_page(page);
_leave(" = %d", ret);
return ret;
}
/*
* read page from file, directory or symlink, given a file to nominate the key
* to be used
*/
static int afs_readpage(struct file *file, struct page *page)
{
struct key *key;
int ret;
if (file) {
key = afs_file_key(file);
ASSERT(key != NULL);
ret = afs_page_filler(key, page);
} else {
struct inode *inode = page->mapping->host;
key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
} else {
ret = afs_page_filler(key, page);
key_put(key);
}
}
return ret;
}
/*
* Make pages available as they're filled.
*/
static void afs_readpages_page_done(struct afs_call *call, struct afs_read *req)
{
#ifdef CONFIG_AFS_FSCACHE
struct afs_vnode *vnode = call->reply[0];
#endif
struct page *page = req->pages[req->index];
req->pages[req->index] = NULL;
SetPageUptodate(page);
/* send the page to the cache */
#ifdef CONFIG_AFS_FSCACHE
if (PageFsCache(page) &&
fscache_write_page(vnode->cache, page, vnode->status.size,
GFP_KERNEL) != 0) {
fscache_uncache_page(vnode->cache, page);
BUG_ON(PageFsCache(page));
}
#endif
unlock_page(page);
put_page(page);
}
/*
* Read a contiguous set of pages.
*/
static int afs_readpages_one(struct file *file, struct address_space *mapping,
struct list_head *pages)
{
struct afs_vnode *vnode = AFS_FS_I(mapping->host);
struct afs_read *req;
struct list_head *p;
struct page *first, *page;
struct key *key = afs_file_key(file);
pgoff_t index;
int ret, n, i;
/* Count the number of contiguous pages at the front of the list. Note
* that the list goes prev-wards rather than next-wards.
*/
first = list_entry(pages->prev, struct page, lru);
index = first->index + 1;
n = 1;
for (p = first->lru.prev; p != pages; p = p->prev) {
page = list_entry(p, struct page, lru);
if (page->index != index)
break;
index++;
n++;
}
req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *) * n,
GFP_NOFS);
if (!req)
return -ENOMEM;
refcount_set(&req->usage, 1);
req->page_done = afs_readpages_page_done;
req->pos = first->index;
req->pos <<= PAGE_SHIFT;
req->pages = req->array;
/* Transfer the pages to the request. We add them in until one fails
* to add to the LRU and then we stop (as that'll make a hole in the
* contiguous run.
*
* Note that it's possible for the file size to change whilst we're
* doing this, but we rely on the server returning less than we asked
* for if the file shrank. We also rely on this to deal with a partial
* page at the end of the file.
*/
do {
page = list_entry(pages->prev, struct page, lru);
list_del(&page->lru);
index = page->index;
if (add_to_page_cache_lru(page, mapping, index,
readahead_gfp_mask(mapping))) {
#ifdef CONFIG_AFS_FSCACHE
fscache_uncache_page(vnode->cache, page);
#endif
put_page(page);
break;
}
req->pages[req->nr_pages++] = page;
req->len += PAGE_SIZE;
} while (req->nr_pages < n);
if (req->nr_pages == 0) {
kfree(req);
return 0;
}
ret = afs_fetch_data(vnode, key, req);
if (ret < 0)
goto error;
task_io_account_read(PAGE_SIZE * req->nr_pages);
afs_put_read(req);
return 0;
error:
if (ret == -ENOENT) {
_debug("got NOENT from server"
" - marking file deleted and stale");
set_bit(AFS_VNODE_DELETED, &vnode->flags);
ret = -ESTALE;
}
for (i = 0; i < req->nr_pages; i++) {
page = req->pages[i];
if (page) {
#ifdef CONFIG_AFS_FSCACHE
fscache_uncache_page(vnode->cache, page);
#endif
SetPageError(page);
unlock_page(page);
}
}
afs_put_read(req);
return ret;
}
/*
* read a set of pages
*/
static int afs_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
struct key *key = afs_file_key(file);
struct afs_vnode *vnode;
int ret = 0;
_enter("{%d},{%lu},,%d",
key_serial(key), mapping->host->i_ino, nr_pages);
ASSERT(key != NULL);
vnode = AFS_FS_I(mapping->host);
if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
_leave(" = -ESTALE");
return -ESTALE;
}
/* attempt to read as many of the pages as possible */
#ifdef CONFIG_AFS_FSCACHE
ret = fscache_read_or_alloc_pages(vnode->cache,
mapping,
pages,
&nr_pages,
afs_file_readpage_read_complete,
NULL,
mapping_gfp_mask(mapping));
#else
ret = -ENOBUFS;
#endif
switch (ret) {
/* all pages are being read from the cache */
case 0:
BUG_ON(!list_empty(pages));
BUG_ON(nr_pages != 0);
_leave(" = 0 [reading all]");
return 0;
/* there were pages that couldn't be read from the cache */
case -ENODATA:
case -ENOBUFS:
break;
/* other error */
default:
_leave(" = %d", ret);
return ret;
}
while (!list_empty(pages)) {
ret = afs_readpages_one(file, mapping, pages);
if (ret < 0)
break;
}
_leave(" = %d [netting]", ret);
return ret;
}
/*
* 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)
{
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
unsigned long priv;
_enter("{%lu},%u,%u", page->index, offset, length);
BUG_ON(!PageLocked(page));
/* we clean up only if the entire page is being invalidated */
if (offset == 0 && length == PAGE_SIZE) {
#ifdef CONFIG_AFS_FSCACHE
if (PageFsCache(page)) {
struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
fscache_wait_on_page_write(vnode->cache, page);
fscache_uncache_page(vnode->cache, page);
}
#endif
if (PagePrivate(page)) {
priv = page_private(page);
trace_afs_page_dirty(vnode, tracepoint_string("inval"),
page->index, priv);
set_page_private(page, 0);
ClearPagePrivate(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);
unsigned long priv;
_enter("{{%x:%u}[%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 (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
_leave(" = F [cache busy]");
return 0;
}
#endif
if (PagePrivate(page)) {
priv = page_private(page);
trace_afs_page_dirty(vnode, tracepoint_string("rel"),
page->index, priv);
set_page_private(page, 0);
ClearPagePrivate(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;
}