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nfs4: resend LAYOUTGET when there is a race that changes the seqid 

pnfs_layout_process will check the returned layout stateid against what
the kernel has in-core. If it turns out that the stateid we received is
older, then we should resend the LAYOUTGET instead of falling back to
MDS I/O.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Cc: stable@vger.kernel.org # 3.18+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Jeff Layton 2015-11-25 13:43:14 -05:00 committed by Trond Myklebust
parent c812012f9c
commit 4f2e9dce0c
1 changed files with 32 additions and 26 deletions
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58
fs/nfs/pnfs.c
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@ -872,33 +872,38 @@ send_layoutget(struct pnfs_layout_hdr *lo,
dprintk("--> %s\n", __func__);
lgp = kzalloc(sizeof(*lgp), gfp_flags);
if (lgp == NULL)
return NULL;
i_size = i_size_read(ino);
lgp->args.minlength = PAGE_CACHE_SIZE;
if (lgp->args.minlength > range->length)
lgp->args.minlength = range->length;
if (range->iomode == IOMODE_READ) {
if (range->offset >= i_size)
lgp->args.minlength = 0;
else if (i_size - range->offset < lgp->args.minlength)
lgp->args.minlength = i_size - range->offset;
}
lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
lgp->args.range = *range;
lgp->args.type = server->pnfs_curr_ld->id;
lgp->args.inode = ino;
lgp->args.ctx = get_nfs_open_context(ctx);
lgp->gfp_flags = gfp_flags;
lgp->cred = lo->plh_lc_cred;
/* Synchronously retrieve layout information from server and
* store in lseg.
/*
* Synchronously retrieve layout information from server and
* store in lseg. If we race with a concurrent seqid morphing
* op, then re-send the LAYOUTGET.
*/
lseg = nfs4_proc_layoutget(lgp, gfp_flags);
do {
lgp = kzalloc(sizeof(*lgp), gfp_flags);
if (lgp == NULL)
return NULL;
i_size = i_size_read(ino);
lgp->args.minlength = PAGE_CACHE_SIZE;
if (lgp->args.minlength > range->length)
lgp->args.minlength = range->length;
if (range->iomode == IOMODE_READ) {
if (range->offset >= i_size)
lgp->args.minlength = 0;
else if (i_size - range->offset < lgp->args.minlength)
lgp->args.minlength = i_size - range->offset;
}
lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
lgp->args.range = *range;
lgp->args.type = server->pnfs_curr_ld->id;
lgp->args.inode = ino;
lgp->args.ctx = get_nfs_open_context(ctx);
lgp->gfp_flags = gfp_flags;
lgp->cred = lo->plh_lc_cred;
lseg = nfs4_proc_layoutget(lgp, gfp_flags);
} while (lseg == ERR_PTR(-EAGAIN));
if (IS_ERR(lseg)) {
switch (PTR_ERR(lseg)) {
case -ENOMEM:
@ -1687,6 +1692,7 @@ pnfs_layout_process(struct nfs4_layoutget *lgp)
/* existing state ID, make sure the sequence number matches. */
if (pnfs_layout_stateid_blocked(lo, &res->stateid)) {
dprintk("%s forget reply due to sequence\n", __func__);
status = -EAGAIN;
goto out_forget_reply;
}
pnfs_set_layout_stateid(lo, &res->stateid, false);