The patch below does not apply to the 3.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 6314efee3cfeea2da12dbc05edfa20e5a42391bd Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@xxxxxxx>
Date: Tue, 1 Oct 2013 16:41:22 +0200
Subject: [PATCH] fuse: readdirplus: fix RCU walk
Doing dput(parent) is not valid in RCU walk mode. In RCU mode it would
probably be okay to update the parent flags, but it's actually not
necessary most of the time...
So only set the FUSE_I_ADVISE_RDPLUS flag on the parent when the entry was
recently initialized by READDIRPLUS.
This is achieved by setting FUSE_I_INIT_RDPLUS on entries added by
READDIRPLUS and only dropping out of RCU mode if this flag is set.
FUSE_I_INIT_RDPLUS is cleared once the FUSE_I_ADVISE_RDPLUS flag is set in
the parent.
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 9b16806..a751598 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -182,6 +182,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
struct inode *inode;
struct dentry *parent;
struct fuse_conn *fc;
+ struct fuse_inode *fi;
int ret;
inode = ACCESS_ONCE(entry->d_inode);
@@ -228,7 +229,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
if (!err && !outarg.nodeid)
err = -ENOENT;
if (!err) {
- struct fuse_inode *fi = get_fuse_inode(inode);
+ fi = get_fuse_inode(inode);
if (outarg.nodeid != get_node_id(inode)) {
fuse_queue_forget(fc, forget, outarg.nodeid, 1);
goto invalid;
@@ -246,8 +247,11 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
attr_version);
fuse_change_entry_timeout(entry, &outarg);
} else if (inode) {
- fc = get_fuse_conn(inode);
- if (fc->readdirplus_auto) {
+ fi = get_fuse_inode(inode);
+ if (flags & LOOKUP_RCU) {
+ if (test_bit(FUSE_I_INIT_RDPLUS, &fi->state))
+ return -ECHILD;
+ } else if (test_and_clear_bit(FUSE_I_INIT_RDPLUS, &fi->state)) {
parent = dget_parent(entry);
fuse_advise_use_readdirplus(parent->d_inode);
dput(parent);
@@ -1292,6 +1296,8 @@ static int fuse_direntplus_link(struct file *file,
}
found:
+ if (fc->readdirplus_auto)
+ set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
fuse_change_entry_timeout(dentry, o);
err = 0;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 5ced199..5b9e6f3 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -115,6 +115,8 @@ struct fuse_inode {
enum {
/** Advise readdirplus */
FUSE_I_ADVISE_RDPLUS,
+ /** Initialized with readdirplus */
+ FUSE_I_INIT_RDPLUS,
/** An operation changing file size is in progress */
FUSE_I_SIZE_UNSTABLE,
};
--
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