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pNFS/flexfiles: Fix a deadlock on LAYOUTGET

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We encountered a deadlock where the SEQUENCE that accompanied the
LAYOUTGET triggered a session drain, while ff_layout_alloc_lseg
triggered a GETDEVICEINFO.  The GETDEVICEINFO hung waiting for the
session drain, while the LAYOUTGET held the slot waiting for
alloc_lseg to finish.
  Avoid this by moving the call to nfs4_find_get_deviceid out of
ff_layout_alloc_lseg and into nfs4_ff_layout_prepare_ds.

Signed-off-by: Fred Isaman <fred.isaman@gmail.com>
[dros@primarydata.com: pNFS/flexfiles: fix races in ff_layout_mirror_valid]
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Fred Isaman
2016-09-30 14:37:41 -04:00
committed by Trond Myklebust
parent 2f065ddb64
commit 65990d1afb
3 changed files with 43 additions and 46 deletions
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2
fs/nfs/flexfilelayout/flexfilelayout.h
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@@ -74,6 +74,7 @@ struct nfs4_ff_layout_mirror {
struct list_head mirrors;
u32 ds_count;
u32 efficiency;
struct nfs4_deviceid devid;
struct nfs4_ff_layout_ds *mirror_ds;
u32 fh_versions_cnt;
struct nfs_fh *fh_versions;
@@ -211,7 +212,6 @@ nfs4_ff_find_or_create_ds_client(struct pnfs_layout_segment *lseg,
struct inode *inode);
struct rpc_cred *ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg,
u32 ds_idx, struct rpc_cred *mdscred);
bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg);
bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg);
bool ff_layout_avoid_read_on_rw(struct pnfs_layout_segment *lseg);