mirrors/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2025-11-04 10:40:15 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

NFS4.1 Fix data server connection race

Browse source 
Unlike meta data server mounts which support multiple mount points to
the same server via struct nfs_server, data servers support a single connection.

Concurrent calls to setup the data server connection can race where the first
call allocates the nfs_client struct, and before the cache struct nfs_client
pointer can be set, a second call also tries to setup the connection, finds the
already allocated nfs_client, bumps the reference count, re-initializes the
session,etc. This results in a hanging data server session after umount.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Andy Adamson 2013-05-08 16:21:18 -04:00 committed by Trond Myklebust
parent d497ab9751
commit c23266d532
2 changed files with 26 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
fs/nfs/nfs4filelayout.h
View file

@ -70,6 +70,8 @@ struct nfs4_pnfs_ds {
struct list_head ds_addrs;
struct nfs_client *ds_clp;
atomic_t ds_count;
unsigned long ds_state;
#define NFS4DS_CONNECTING 0 /* ds is establishing connection */
};
struct nfs4_file_layout_dsaddr {

26
fs/nfs/nfs4filelayoutdev.c
View file

@ -775,6 +775,22 @@ nfs4_fl_select_ds_fh(struct pnfs_layout_segment *lseg, u32 j)
return flseg->fh_array[i];
}
static void nfs4_wait_ds_connect(struct nfs4_pnfs_ds *ds)
{
might_sleep();
wait_on_bit(&ds->ds_state, NFS4DS_CONNECTING,
nfs_wait_bit_killable, TASK_KILLABLE);
}
static void nfs4_clear_ds_conn_bit(struct nfs4_pnfs_ds *ds)
{
smp_mb__before_clear_bit();
clear_bit(NFS4DS_CONNECTING, &ds->ds_state);
smp_mb__after_clear_bit();
wake_up_bit(&ds->ds_state, NFS4DS_CONNECTING);
}
struct nfs4_pnfs_ds *
nfs4_fl_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx)
{
@ -791,16 +807,22 @@ nfs4_fl_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx)
filelayout_mark_devid_invalid(devid);
return NULL;
}
if (ds->ds_clp)
return ds;
if (!ds->ds_clp) {
if (test_and_set_bit(NFS4DS_CONNECTING, &ds->ds_state) == 0) {
struct nfs_server *s = NFS_SERVER(lseg->pls_layout->plh_inode);
int err;
err = nfs4_ds_connect(s, ds);
if (err) {
nfs4_mark_deviceid_unavailable(devid);
return NULL;
ds = NULL;
}
nfs4_clear_ds_conn_bit(ds);
} else {
/* Either ds is connected, or ds is NULL */
nfs4_wait_ds_connect(ds);
}
return ds;
}