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nfsd: protect lease-related nfs4_file fields with fi_lock

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Currently these fields are protected with the state_lock, but that
doesn't really make a lot of sense. These fields are "private" to the
nfs4_file, and can be protected with the more granular fi_lock.

The fi_lock is already held when setting these fields. Make the code
hold the fp->fi_lock when clearing the lease-related fields in the
nfs4_file, and no longer require that the state_lock be held when
calling into this function.

To prevent lock inversion with the i_lock, we also move the vfs_setlease
and fput calls outside of the fi_lock. This also sets us up for allowing
vfs_setlease calls to block in the future.

Finally, remove a redundant NULL pointer check. unhash_delegation_locked
locks the fp->fi_lock prior to that check, so fp in that function must
never be NULL.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Jeff Layton 2014-08-09 10:22:40 -04:00 committed by J. Bruce Fields
parent ef9b16dc6d
commit 6bcc034eac
1 changed files with 13 additions and 9 deletions
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20
fs/nfsd/nfs4state.c
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@ -673,15 +673,20 @@ nfs4_put_stid(struct nfs4_stid *s)
static void nfs4_put_deleg_lease(struct nfs4_file *fp)
{
lockdep_assert_held(&state_lock);
struct file *filp = NULL;
struct file_lock *fl;
if (!fp->fi_lease)
return;
if (atomic_dec_and_test(&fp->fi_delegees)) {
vfs_setlease(fp->fi_deleg_file, F_UNLCK, &fp->fi_lease);
spin_lock(&fp->fi_lock);
if (fp->fi_lease && atomic_dec_and_test(&fp->fi_delegees)) {
swap(filp, fp->fi_deleg_file);
fl = fp->fi_lease;
fp->fi_lease = NULL;
fput(fp->fi_deleg_file);
fp->fi_deleg_file = NULL;
}
spin_unlock(&fp->fi_lock);
if (filp) {
vfs_setlease(filp, F_UNLCK, &fl);
fput(filp);
}
}
@ -717,7 +722,6 @@ unhash_delegation_locked(struct nfs4_delegation *dp)
list_del_init(&dp->dl_recall_lru);
list_del_init(&dp->dl_perfile);
spin_unlock(&fp->fi_lock);
if (fp)
nfs4_put_deleg_lease(fp);
}