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Commit b4e28099 authored by Jeff Layton's avatar Jeff Layton Committed by Greg Kroah-Hartman
Browse files

nfsd: don't call nfsd_file_put from client states seqfile display 

[ Upstream commit e0aa651068bfd520afcd357af8ecd2de005fc83d ]

We had a report of this:

    BUG: sleeping function called from invalid context at fs/nfsd/filecache.c:440

...with a stack trace showing nfsd_file_put being called from
nfs4_show_open. This code has always tried to call fput while holding a
spinlock, but we recently changed this to use the filecache, and that
started triggering the might_sleep() in nfsd_file_put.

states_start takes and holds the cl_lock while iterating over the
client's states, and we can't sleep with that held.

Have the various nfs4_show_* functions instead hold the fi_lock instead
of taking a nfsd_file reference.

Fixes: 78599c42 ("nfsd4: add file to display list of client's opens")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2138357


Reported-by: default avatarZhi Li <yieli@redhat.com>
Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent e6e295a4

fs/nfsd/nfs4state.c

+33 −18
Original line number Diff line number Diff line
@@ -508,15 +508,26 @@ find_any_file(struct nfs4_file *f) 
	return ret;

}



static struct nfsd_file *find_deleg_file(struct nfs4_file *f)

static struct nfsd_file *find_any_file_locked(struct nfs4_file *f)

{

	struct nfsd_file *ret = NULL;

	lockdep_assert_held(&f->fi_lock);



	if (f->fi_fds[O_RDWR])

		return f->fi_fds[O_RDWR];

	if (f->fi_fds[O_WRONLY])

		return f->fi_fds[O_WRONLY];

	if (f->fi_fds[O_RDONLY])

		return f->fi_fds[O_RDONLY];

	return NULL;

}



static struct nfsd_file *find_deleg_file_locked(struct nfs4_file *f)

{

	lockdep_assert_held(&f->fi_lock);



	spin_lock(&f->fi_lock);

	if (f->fi_deleg_file)

		ret = nfsd_file_get(f->fi_deleg_file);

	spin_unlock(&f->fi_lock);

	return ret;

		return f->fi_deleg_file;

	return NULL;

}



static atomic_long_t num_delegations;
@@ -2402,9 +2413,11 @@ static int nfs4_show_open(struct seq_file *s, struct nfs4_stid *st) 
	ols = openlockstateid(st);

	oo = ols->st_stateowner;

	nf = st->sc_file;

	file = find_any_file(nf);



	spin_lock(&nf->fi_lock);

	file = find_any_file_locked(nf);

	if (!file)

		return 0;

		goto out;



	seq_printf(s, "- 0x%16phN: { type: open, ", &st->sc_stateid);
@@ -2422,8 +2435,8 @@ static int nfs4_show_open(struct seq_file *s, struct nfs4_stid *st) 
	seq_printf(s, ", ");

	nfs4_show_owner(s, oo);

	seq_printf(s, " }\n");

	nfsd_file_put(file);



out:

	spin_unlock(&nf->fi_lock);

	return 0;

}
@@ -2437,9 +2450,10 @@ static int nfs4_show_lock(struct seq_file *s, struct nfs4_stid *st) 
	ols = openlockstateid(st);

	oo = ols->st_stateowner;

	nf = st->sc_file;

	file = find_any_file(nf);

	spin_lock(&nf->fi_lock);

	file = find_any_file_locked(nf);

	if (!file)

		return 0;

		goto out;



	seq_printf(s, "- 0x%16phN: { type: lock, ", &st->sc_stateid);
@@ -2455,8 +2469,8 @@ static int nfs4_show_lock(struct seq_file *s, struct nfs4_stid *st) 
	seq_printf(s, ", ");

	nfs4_show_owner(s, oo);

	seq_printf(s, " }\n");

	nfsd_file_put(file);



out:

	spin_unlock(&nf->fi_lock);

	return 0;

}
@@ -2468,9 +2482,10 @@ static int nfs4_show_deleg(struct seq_file *s, struct nfs4_stid *st) 


	ds = delegstateid(st);

	nf = st->sc_file;

	file = find_deleg_file(nf);

	spin_lock(&nf->fi_lock);

	file = find_deleg_file_locked(nf);

	if (!file)

		return 0;

		goto out;



	seq_printf(s, "- 0x%16phN: { type: deleg, ", &st->sc_stateid);
@@ -2482,8 +2497,8 @@ static int nfs4_show_deleg(struct seq_file *s, struct nfs4_stid *st) 


	nfs4_show_superblock(s, file);

	seq_printf(s, " }\n");

	nfsd_file_put(file);



out:

	spin_unlock(&nf->fi_lock);

	return 0;

}