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43c36a56cc
This reverts commit290434474c. That commit broke cache=mmap, a mode that doesn't cache metadata, but still has writeback cache. In commit290434474c("fs/9p: Refresh metadata in d_revalidate for uncached mode too") we considered metadata cache to be enough to not look at the server, but in writeback cache too looking at the server size would make the vfs consider the file has been truncated before the data has been flushed out, making the following repro fail (nothing is ever read back, the resulting file ends up with no data written) ``` #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> char buf[4096]; int main(int argc, char *argv[]) { int ret, i; int fdw, fdr; if (argc < 2) return 1; fdw = openat(AT_FDCWD, argv[1], O_RDWR|O_CREAT|O_EXCL|O_CLOEXEC, 0600); if (fdw < 0) { fprintf(stderr, "cannot open fdw\n"); return 1; } write(fdw, buf, sizeof(buf)); fdr = openat(AT_FDCWD, argv[1], O_RDONLY|O_CLOEXEC); if (fdr < 0) { fprintf(stderr, "cannot open fdr\n"); close(fdw); return 1; } for (i = 0; i < 10; i++) { ret = read(fdr, buf, sizeof(buf)); fprintf(stderr, "i: %d, read returns %d\n", i, ret); } close(fdr); close(fdw); return 0; } ``` There is a fix for this particular reproducer but it looks like there are other problems around metadata refresh (e.g. around file rename), so revert this to avoid d_revalidate in uncached mode for now. Reported-by: Song Liu <song@kernel.org> Link: https://lkml.kernel.org/r/CAHzjS_u_SYdt5=2gYO_dxzMKXzGMt-TfdE_ueowg-Hq5tRCAiw@mail.gmail.com Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com> Link: https://lore.kernel.org/bpf/CAEf4BzZbCE4tLoDZyUf_aASpgAGFj75QMfSXX4a4dLYixnOiLg@mail.gmail.com/ Fixes:290434474c("fs/9p: Refresh metadata in d_revalidate for uncached mode too") Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
153 lines
3.8 KiB
C
153 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* This file contians vfs dentry ops for the 9P2000 protocol.
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*
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* Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
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* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
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*/
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/pagemap.h>
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#include <linux/stat.h>
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#include <linux/string.h>
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#include <linux/namei.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <net/9p/9p.h>
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#include <net/9p/client.h>
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#include "v9fs.h"
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#include "v9fs_vfs.h"
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#include "fid.h"
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/**
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* v9fs_cached_dentry_delete - called when dentry refcount equals 0
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* @dentry: dentry in question
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*
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*/
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static int v9fs_cached_dentry_delete(const struct dentry *dentry)
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{
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p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n",
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dentry, dentry);
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/* Don't cache negative dentries */
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if (d_really_is_negative(dentry))
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return 1;
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return 0;
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}
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/**
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* v9fs_dentry_release - called when dentry is going to be freed
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* @dentry: dentry that is being release
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*
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*/
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static void v9fs_dentry_release(struct dentry *dentry)
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{
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struct hlist_node *p, *n;
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struct hlist_head head;
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p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n",
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dentry, dentry);
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spin_lock(&dentry->d_lock);
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hlist_move_list((struct hlist_head *)&dentry->d_fsdata, &head);
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spin_unlock(&dentry->d_lock);
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hlist_for_each_safe(p, n, &head)
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p9_fid_put(hlist_entry(p, struct p9_fid, dlist));
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}
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static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct p9_fid *fid;
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struct inode *inode;
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struct v9fs_inode *v9inode;
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if (flags & LOOKUP_RCU)
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return -ECHILD;
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inode = d_inode(dentry);
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if (!inode)
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goto out_valid;
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v9inode = V9FS_I(inode);
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if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
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int retval;
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struct v9fs_session_info *v9ses;
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fid = v9fs_fid_lookup(dentry);
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if (IS_ERR(fid)) {
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p9_debug(
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P9_DEBUG_VFS,
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"v9fs_fid_lookup: dentry = %pd (%p), got error %pe\n",
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dentry, dentry, fid);
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return PTR_ERR(fid);
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}
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v9ses = v9fs_inode2v9ses(inode);
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if (v9fs_proto_dotl(v9ses))
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retval = v9fs_refresh_inode_dotl(fid, inode);
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else
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retval = v9fs_refresh_inode(fid, inode);
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p9_fid_put(fid);
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if (retval == -ENOENT) {
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p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to ENOENT\n",
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dentry, dentry);
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return 0;
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}
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if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
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p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to type change\n",
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dentry, dentry);
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return 0;
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}
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if (retval < 0) {
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p9_debug(P9_DEBUG_VFS,
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"refresh inode: dentry = %pd (%p), got error %pe\n",
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dentry, dentry, ERR_PTR(retval));
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if (retval < 0)
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return retval;
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}
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}
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out_valid:
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p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) is valid\n", dentry, dentry);
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return 1;
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}
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static int v9fs_lookup_revalidate(struct inode *dir, const struct qstr *name,
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struct dentry *dentry, unsigned int flags)
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{
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return __v9fs_lookup_revalidate(dentry, flags);
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}
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static bool v9fs_dentry_unalias_trylock(const struct dentry *dentry)
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{
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struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
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return down_write_trylock(&v9ses->rename_sem);
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}
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static void v9fs_dentry_unalias_unlock(const struct dentry *dentry)
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{
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struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
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up_write(&v9ses->rename_sem);
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}
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const struct dentry_operations v9fs_cached_dentry_operations = {
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.d_revalidate = v9fs_lookup_revalidate,
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.d_weak_revalidate = __v9fs_lookup_revalidate,
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.d_delete = v9fs_cached_dentry_delete,
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.d_release = v9fs_dentry_release,
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.d_unalias_trylock = v9fs_dentry_unalias_trylock,
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.d_unalias_unlock = v9fs_dentry_unalias_unlock,
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};
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const struct dentry_operations v9fs_dentry_operations = {
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.d_release = v9fs_dentry_release,
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.d_unalias_trylock = v9fs_dentry_unalias_trylock,
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.d_unalias_unlock = v9fs_dentry_unalias_unlock,
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};
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