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

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[ Upstream commit e0aa651068 ]

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: 78599c42ae ("nfsd4: add file to display list of client's opens")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2138357
Reported-by: Zhi Li <yieli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jeff Layton 2022-10-28 08:13:53 -04:00 committed by Greg Kroah-Hartman
parent 5030d4d2bf
commit 435cc7d18c
1 changed files with 33 additions and 18 deletions
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51
fs/nfsd/nfs4state.c
View File

@ -627,15 +627,26 @@ find_any_file(struct nfs4_file *f)
return ret; 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) if (f->fi_deleg_file)
ret = nfsd_file_get(f->fi_deleg_file); return f->fi_deleg_file;
spin_unlock(&f->fi_lock); return NULL;
return ret;
} }
static atomic_long_t num_delegations; static atomic_long_t num_delegations;
@ -2501,9 +2512,11 @@ static int nfs4_show_open(struct seq_file *s, struct nfs4_stid *st)
ols = openlockstateid(st); ols = openlockstateid(st);
oo = ols->st_stateowner; oo = ols->st_stateowner;
nf = st->sc_file; nf = st->sc_file;
file = find_any_file(nf);
spin_lock(&nf->fi_lock);
file = find_any_file_locked(nf);
if (!file) if (!file)
return 0; goto out;
seq_printf(s, "- "); seq_printf(s, "- ");
nfs4_show_stateid(s, &st->sc_stateid); nfs4_show_stateid(s, &st->sc_stateid);
@ -2525,8 +2538,8 @@ static int nfs4_show_open(struct seq_file *s, struct nfs4_stid *st)
seq_printf(s, ", "); seq_printf(s, ", ");
nfs4_show_owner(s, oo); nfs4_show_owner(s, oo);
seq_printf(s, " }\n"); seq_printf(s, " }\n");
nfsd_file_put(file); out:
spin_unlock(&nf->fi_lock);
return 0; return 0;
} }
@ -2540,9 +2553,10 @@ static int nfs4_show_lock(struct seq_file *s, struct nfs4_stid *st)
ols = openlockstateid(st); ols = openlockstateid(st);
oo = ols->st_stateowner; oo = ols->st_stateowner;
nf = st->sc_file; nf = st->sc_file;
file = find_any_file(nf); spin_lock(&nf->fi_lock);
file = find_any_file_locked(nf);
if (!file) if (!file)
return 0; goto out;
seq_printf(s, "- "); seq_printf(s, "- ");
nfs4_show_stateid(s, &st->sc_stateid); nfs4_show_stateid(s, &st->sc_stateid);
@ -2562,8 +2576,8 @@ static int nfs4_show_lock(struct seq_file *s, struct nfs4_stid *st)
seq_printf(s, ", "); seq_printf(s, ", ");
nfs4_show_owner(s, oo); nfs4_show_owner(s, oo);
seq_printf(s, " }\n"); seq_printf(s, " }\n");
nfsd_file_put(file); out:
spin_unlock(&nf->fi_lock);
return 0; return 0;
} }
@ -2575,9 +2589,10 @@ static int nfs4_show_deleg(struct seq_file *s, struct nfs4_stid *st)
ds = delegstateid(st); ds = delegstateid(st);
nf = st->sc_file; nf = st->sc_file;
file = find_deleg_file(nf); spin_lock(&nf->fi_lock);
file = find_deleg_file_locked(nf);
if (!file) if (!file)
return 0; goto out;
seq_printf(s, "- "); seq_printf(s, "- ");
nfs4_show_stateid(s, &st->sc_stateid); nfs4_show_stateid(s, &st->sc_stateid);
@ -2593,8 +2608,8 @@ static int nfs4_show_deleg(struct seq_file *s, struct nfs4_stid *st)
seq_printf(s, ", "); seq_printf(s, ", ");
nfs4_show_fname(s, file); nfs4_show_fname(s, file);
seq_printf(s, " }\n"); seq_printf(s, " }\n");
nfsd_file_put(file); out:
spin_unlock(&nf->fi_lock);
return 0; return 0;
} }