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@xxxxxxxxxxxxxxx>
---
fs/nfs/pnfs.c | 118 ++++++++++++++++++++++++++++------------------------------
1 file changed, 56 insertions(+), 62 deletions(-)
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index a3592cc34a20..9c20685d4961 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -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.
--
2.5.0
--
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