24e42e32d3
Change the 9p filesystem to take account of the changes to fscache's
indexing rewrite and reenable caching in 9p.
The following changes have been made:
(1) The fscache_netfs struct is no more, and there's no need to register
the filesystem as a whole.
(2) The session cookie is now an fscache_volume cookie, allocated with
fscache_acquire_volume(). That takes three parameters: a string
representing the "volume" in the index, a string naming the cache to
use (or NULL) and a u64 that conveys coherency metadata for the
volume.
For 9p, I've made it render the volume name string as:
"9p,<devname>,<cachetag>"
where the cachetag is replaced by the aname if it wasn't supplied.
This probably needs rethinking a bit as the aname can have slashes in
it. It might be better to hash the cachetag and use the hash or I
could substitute commas for the slashes or something.
(3) The fscache_cookie_def is no more and needed information is passed
directly to fscache_acquire_cookie(). The cache no longer calls back
into the filesystem, but rather metadata changes are indicated at
other times.
fscache_acquire_cookie() is passed the same keying and coherency
information as before.
(4) The functions to set/reset/flush cookies are removed and
fscache_use_cookie() and fscache_unuse_cookie() are used instead.
fscache_use_cookie() is passed a flag to indicate if the cookie is
opened for writing. fscache_unuse_cookie() is passed updates for the
metadata if we changed it (ie. if the file was opened for writing).
These are called when the file is opened or closed.
(5) wait_on_page_bit[_killable]() is replaced with the specific wait
functions for the bits waited upon.
(6) I've got rid of some of the 9p-specific cache helper functions and
called things like fscache_relinquish_cookie() directly as they'll
optimise away if v9fs_inode_cookie() returns an unconditional NULL
(which will be the case if CONFIG_9P_FSCACHE=n).
(7) v9fs_vfs_setattr() is made to call fscache_resize() to change the size
of the cache object.
Notes:
(A) We should call fscache_invalidate() if we detect that the server's
copy of a file got changed by a third party, but I don't know where to
do that. We don't need to do that when allocating the cookie as we
get a check-and-invalidate when we initially bind to the cache object.
(B) The copy-to-cache-on-writeback side of things will be handled in
separate patch.
Changes
=======
ver #3:
- Canonicalise the cookie key and coherency data to make them
endianness-independent.
ver #2:
- Use gfpflags_allow_blocking() rather than using flag directly.
- fscache_acquire_volume() now returns errors.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dominique Martinet <asmadeus@codewreck.org>
cc: Eric Van Hensbergen <ericvh@gmail.com>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: v9fs-developer@lists.sourceforge.net
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819664645.215744.1555314582005286846.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906975017.143852.3459573173204394039.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967178512.1823006.17377493641569138183.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021573143.640689.3977487095697717967.stgit@warthog.procyon.org.uk/ # v4
77 lines
1.7 KiB
C
77 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* V9FS cache definitions.
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*
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* Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
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*/
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#include <linux/jiffies.h>
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#include <linux/file.h>
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <net/9p/9p.h>
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#include "v9fs.h"
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#include "cache.h"
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int v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses,
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const char *dev_name)
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{
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struct fscache_volume *vcookie;
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char *name, *p;
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name = kasprintf(GFP_KERNEL, "9p,%s,%s",
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dev_name, v9ses->cachetag ?: v9ses->aname);
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if (!name)
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return -ENOMEM;
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for (p = name; *p; p++)
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if (*p == '/')
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*p = ';';
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vcookie = fscache_acquire_volume(name, NULL, NULL, 0);
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p9_debug(P9_DEBUG_FSC, "session %p get volume %p (%s)\n",
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v9ses, vcookie, name);
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if (IS_ERR(vcookie)) {
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if (vcookie != ERR_PTR(-EBUSY)) {
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kfree(name);
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return PTR_ERR(vcookie);
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}
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pr_err("Cache volume key already in use (%s)\n", name);
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vcookie = NULL;
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}
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v9ses->fscache = vcookie;
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kfree(name);
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return 0;
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}
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void v9fs_cache_inode_get_cookie(struct inode *inode)
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{
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struct v9fs_inode *v9inode;
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struct v9fs_session_info *v9ses;
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__le32 version;
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__le64 path;
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if (!S_ISREG(inode->i_mode))
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return;
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v9inode = V9FS_I(inode);
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if (WARN_ON(v9inode->fscache))
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return;
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version = cpu_to_le32(v9inode->qid.version);
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path = cpu_to_le64(v9inode->qid.path);
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v9ses = v9fs_inode2v9ses(inode);
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v9inode->fscache =
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fscache_acquire_cookie(v9fs_session_cache(v9ses),
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0,
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&path, sizeof(path),
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&version, sizeof(version),
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i_size_read(&v9inode->vfs_inode));
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p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
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inode, v9inode->fscache);
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}
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