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NFSv4.1: Fix a race in pNFS layoutcommit

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We need to clear the NFS_LSEG_LAYOUTCOMMIT bits atomically with the
NFS_INO_LAYOUTCOMMIT bit, otherwise we may end up with situations
where the two are out of sync.
The first half of the problem is to ensure that pnfs_layoutcommit_inode
clears the NFS_LSEG_LAYOUTCOMMIT bit through pnfs_list_write_lseg.
We still need to keep the reference to those segments until the RPC call
is finished, so in order to make it clear _where_ those references come
from, we add a helper pnfs_list_write_lseg_done() that cleans up after
pnfs_list_write_lseg.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Benny Halevy <bhalevy@tonian.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Trond Myklebust 2013-03-20 12:34:32 -04:00
parent 4376c94618
commit a073dbff35
2 changed files with 18 additions and 15 deletions
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14
fs/nfs/nfs4proc.c
View File

@ -6416,22 +6416,8 @@ nfs4_layoutcommit_done(struct rpc_task *task, void *calldata)
static void nfs4_layoutcommit_release(void *calldata)
{
struct nfs4_layoutcommit_data *data = calldata;
struct pnfs_layout_segment *lseg, *tmp;
unsigned long *bitlock = &NFS_I(data->args.inode)->flags;
pnfs_cleanup_layoutcommit(data);
/* Matched by references in pnfs_set_layoutcommit */
list_for_each_entry_safe(lseg, tmp, &data->lseg_list, pls_lc_list) {
list_del_init(&lseg->pls_lc_list);
if (test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT,
&lseg->pls_flags))
pnfs_put_lseg(lseg);
}
clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock);
smp_mb__after_clear_bit();
wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING);
put_rpccred(data->cred);
kfree(data);
}

19
fs/nfs/pnfs.c
View File

@ -1746,11 +1746,27 @@ static void pnfs_list_write_lseg(struct inode *inode, struct list_head *listp)
list_for_each_entry(lseg, &NFS_I(inode)->layout->plh_segs, pls_list) {
if (lseg->pls_range.iomode == IOMODE_RW &&
test_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))
test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))
list_add(&lseg->pls_lc_list, listp);
}
}
static void pnfs_list_write_lseg_done(struct inode *inode, struct list_head *listp)
{
struct pnfs_layout_segment *lseg, *tmp;
unsigned long *bitlock = &NFS_I(inode)->flags;
/* Matched by references in pnfs_set_layoutcommit */
list_for_each_entry_safe(lseg, tmp, listp, pls_lc_list) {
list_del_init(&lseg->pls_lc_list);
pnfs_put_lseg(lseg);
}
clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock);
smp_mb__after_clear_bit();
wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING);
}
void pnfs_set_lo_fail(struct pnfs_layout_segment *lseg)
{
pnfs_layout_io_set_failed(lseg->pls_layout, lseg->pls_range.iomode);
@ -1795,6 +1811,7 @@ void pnfs_cleanup_layoutcommit(struct nfs4_layoutcommit_data *data)
if (nfss->pnfs_curr_ld->cleanup_layoutcommit)
nfss->pnfs_curr_ld->cleanup_layoutcommit(data);
pnfs_list_write_lseg_done(data->args.inode, &data->lseg_list);
}
/*