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pNFS: Fix a deadlock between read resends and layoutreturn 

We must not call nfs_pageio_init_read() on a new nfs_pageio_descriptor
while holding a reference to a layout segment, as that can deadlock
pnfs_update_layout().

Fixes: d67ae825a5 ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v4.0+
hifive-unleashed-5.1
Trond Myklebust 2016-11-27 15:12:39 -05:00
parent 9a837856cf
commit 54e4a0dfa2
2 changed files with 8 additions and 0 deletions
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4
fs/nfs/flexfilelayout/flexfilelayout.c
View File

@ -28,6 +28,9 @@
static struct group_info *ff_zero_group;
static void ff_layout_read_record_layoutstats_done(struct rpc_task *task,
struct nfs_pgio_header *hdr);
static struct pnfs_layout_hdr *
ff_layout_alloc_layout_hdr(struct inode *inode, gfp_t gfp_flags)
{
@ -1293,6 +1296,7 @@ static int ff_layout_read_done_cb(struct rpc_task *task,
hdr->pgio_mirror_idx + 1,
&hdr->pgio_mirror_idx))
goto out_eagain;
ff_layout_read_record_layoutstats_done(task, hdr);
pnfs_read_resend_pnfs(hdr);
return task->tk_status;
case -NFS4ERR_RESET_TO_MDS:

4
fs/nfs/pnfs.c
View File

@ -2286,6 +2286,10 @@ void pnfs_read_resend_pnfs(struct nfs_pgio_header *hdr)
struct nfs_pageio_descriptor pgio;
if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
/* Prevent deadlocks with layoutreturn! */
pnfs_put_lseg(hdr->lseg);
hdr->lseg = NULL;
nfs_pageio_init_read(&pgio, hdr->inode, false,
hdr->completion_ops);
hdr->task.tk_status = nfs_pageio_resend(&pgio, hdr);