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pNFS: Fix missing layoutreturn calls

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The layoutreturn code currently relies on pnfs_put_lseg() to initiate the
RPC call when conditions are right. A problem arises when we want to
free the layout segment from inside an inode->i_lock section (e.g. in
pnfs_clear_request_commit()), since we cannot sleep.

The workaround is to move the actual call to pnfs_send_layoutreturn()
to pnfs_put_layout_hdr(), which doesn't have this restriction.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2016-01-26 23:12:11 -05:00
parent 92e963f50f
commit 13c13a6ad7
1 changed files with 56 additions and 62 deletions
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118
fs/nfs/pnfs.c
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@ -52,9 +52,7 @@ static DEFINE_SPINLOCK(pnfs_spinlock);
*/
static LIST_HEAD(pnfs_modules_tbl);
static int
pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, const nfs4_stateid *stateid,
enum pnfs_iomode iomode, bool sync);
static void pnfs_layoutreturn_before_put_layout_hdr(struct pnfs_layout_hdr *lo);
/* Return the registered pnfs layout driver module matching given id */
static struct pnfs_layoutdriver_type *
@ -243,6 +241,8 @@ pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo)
{
struct inode *inode = lo->plh_inode;
pnfs_layoutreturn_before_put_layout_hdr(lo);
if (atomic_dec_and_lock(&lo->plh_refcount, &inode->i_lock)) {
if (!list_empty(&lo->plh_segs))
WARN_ONCE(1, "NFS: BUG unfreed layout segments.\n");
@ -345,58 +345,6 @@ pnfs_layout_remove_lseg(struct pnfs_layout_hdr *lo,
rpc_wake_up(&NFS_SERVER(inode)->roc_rpcwaitq);
}
/* Return true if layoutreturn is needed */
static bool
pnfs_layout_need_return(struct pnfs_layout_hdr *lo,
struct pnfs_layout_segment *lseg)
{
struct pnfs_layout_segment *s;
if (!test_and_clear_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))
return false;
list_for_each_entry(s, &lo->plh_segs, pls_list)
if (s != lseg && test_bit(NFS_LSEG_LAYOUTRETURN, &s->pls_flags))
return false;
return true;
}
static bool
pnfs_prepare_layoutreturn(struct pnfs_layout_hdr *lo)
{
if (test_and_set_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
return false;
lo->plh_return_iomode = 0;
pnfs_get_layout_hdr(lo);
clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags);
return true;
}
static void pnfs_layoutreturn_before_put_lseg(struct pnfs_layout_segment *lseg,
struct pnfs_layout_hdr *lo, struct inode *inode)
{
lo = lseg->pls_layout;
inode = lo->plh_inode;
spin_lock(&inode->i_lock);
if (pnfs_layout_need_return(lo, lseg)) {
nfs4_stateid stateid;
enum pnfs_iomode iomode;
bool send;
nfs4_stateid_copy(&stateid, &lo->plh_stateid);
iomode = lo->plh_return_iomode;
send = pnfs_prepare_layoutreturn(lo);
spin_unlock(&inode->i_lock);
if (send) {
/* Send an async layoutreturn so we dont deadlock */
pnfs_send_layoutreturn(lo, &stateid, iomode, false);
}
} else
spin_unlock(&inode->i_lock);
}
void
pnfs_put_lseg(struct pnfs_layout_segment *lseg)
{
@ -410,15 +358,8 @@ pnfs_put_lseg(struct pnfs_layout_segment *lseg)
atomic_read(&lseg->pls_refcount),
test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
/* Handle the case where refcount != 1 */
if (atomic_add_unless(&lseg->pls_refcount, -1, 1))
return;
lo = lseg->pls_layout;
inode = lo->plh_inode;
/* Do we need a layoutreturn? */
if (test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))
pnfs_layoutreturn_before_put_lseg(lseg, lo, inode);
if (atomic_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
@ -937,6 +878,17 @@ void pnfs_clear_layoutreturn_waitbit(struct pnfs_layout_hdr *lo)
rpc_wake_up(&NFS_SERVER(lo->plh_inode)->roc_rpcwaitq);
}
static bool
pnfs_prepare_layoutreturn(struct pnfs_layout_hdr *lo)
{
if (test_and_set_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
return false;
lo->plh_return_iomode = 0;
pnfs_get_layout_hdr(lo);
clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags);
return true;
}
static int
pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, const nfs4_stateid *stateid,
enum pnfs_iomode iomode, bool sync)
@ -971,6 +923,48 @@ out:
return status;
}
/* Return true if layoutreturn is needed */
static bool
pnfs_layout_need_return(struct pnfs_layout_hdr *lo)
{
struct pnfs_layout_segment *s;
if (!test_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags))
return false;
/* Defer layoutreturn until all lsegs are done */
list_for_each_entry(s, &lo->plh_segs, pls_list) {
if (test_bit(NFS_LSEG_LAYOUTRETURN, &s->pls_flags))
return false;
}
return true;
}
static void pnfs_layoutreturn_before_put_layout_hdr(struct pnfs_layout_hdr *lo)
{
struct inode *inode= lo->plh_inode;
if (!test_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags))
return;
spin_lock(&inode->i_lock);
if (pnfs_layout_need_return(lo)) {
nfs4_stateid stateid;
enum pnfs_iomode iomode;
bool send;
nfs4_stateid_copy(&stateid, &lo->plh_stateid);
iomode = lo->plh_return_iomode;
send = pnfs_prepare_layoutreturn(lo);
spin_unlock(&inode->i_lock);
if (send) {
/* Send an async layoutreturn so we dont deadlock */
pnfs_send_layoutreturn(lo, &stateid, iomode, false);
}
} else
spin_unlock(&inode->i_lock);
}
/*
* Initiates a LAYOUTRETURN(FILE), and removes the pnfs_layout_hdr
* when the layout segment list is empty.