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NFSv4.2: Rework scratch handling for READ_PLUS

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Instead of using a tiny, static scratch buffer, we should use a kmalloc()-ed
buffer that is allocated when checking for read plus usage. This lets us
use the buffer before decoding any part of the READ_PLUS operation
instead of setting it right before segment decoding, meaning it should
be a little more robust.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Anna Schumaker 2023-04-06 15:16:52 -04:00
parent e025f0a73f
commit fbd2a05f29
3 changed files with 15 additions and 7 deletions
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4
fs/nfs/nfs42xdr.c
View File

@ -1122,7 +1122,6 @@ static int decode_read_plus(struct xdr_stream *xdr, struct nfs_pgio_res *res)
uint32_t segments;
struct read_plus_segment *segs;
int status, i;
char scratch_buf[16];
__be32 *p;
status = decode_op_hdr(xdr, OP_READ_PLUS);
@ -1143,7 +1142,6 @@ static int decode_read_plus(struct xdr_stream *xdr, struct nfs_pgio_res *res)
if (!segs)
return -ENOMEM;
xdr_set_scratch_buffer(xdr, &scratch_buf, sizeof(scratch_buf));
status = -EIO;
for (i = 0; i < segments; i++) {
status = decode_read_plus_segment(xdr, &segs[i]);
@ -1348,6 +1346,8 @@ static int nfs4_xdr_dec_read_plus(struct rpc_rqst *rqstp,
struct compound_hdr hdr;
int status;
xdr_set_scratch_buffer(xdr, res->scratch, sizeof(res->scratch));
status = decode_compound_hdr(xdr, &hdr);
if (status)
goto out;

17
fs/nfs/nfs4proc.c
View File

@ -5439,6 +5439,8 @@ static bool nfs4_read_plus_not_supported(struct rpc_task *task,
static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr)
{
if (hdr->res.scratch)
kfree(hdr->res.scratch);
if (!nfs4_sequence_done(task, &hdr->res.seq_res))
return -EAGAIN;
if (nfs4_read_stateid_changed(task, &hdr->args))
@ -5452,17 +5454,22 @@ static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr)
}
#if defined CONFIG_NFS_V4_2 && defined CONFIG_NFS_V4_2_READ_PLUS
static void nfs42_read_plus_support(struct nfs_pgio_header *hdr,
static bool nfs42_read_plus_support(struct nfs_pgio_header *hdr,
struct rpc_message *msg)
{
/* Note: We don't use READ_PLUS with pNFS yet */
if (nfs_server_capable(hdr->inode, NFS_CAP_READ_PLUS) && !hdr->ds_clp)
if (nfs_server_capable(hdr->inode, NFS_CAP_READ_PLUS) && !hdr->ds_clp) {
msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ_PLUS];
hdr->res.scratch = kmalloc(32, GFP_KERNEL);
return hdr->res.scratch != NULL;
}
return false;
}
#else
static void nfs42_read_plus_support(struct nfs_pgio_header *hdr,
static bool nfs42_read_plus_support(struct nfs_pgio_header *hdr,
struct rpc_message *msg)
{
return false;
}
#endif /* CONFIG_NFS_V4_2 */
@ -5472,8 +5479,8 @@ static void nfs4_proc_read_setup(struct nfs_pgio_header *hdr,
hdr->timestamp = jiffies;
if (!hdr->pgio_done_cb)
hdr->pgio_done_cb = nfs4_read_done_cb;
msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
nfs42_read_plus_support(hdr, msg);
if (!nfs42_read_plus_support(hdr, msg))
msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
nfs4_init_sequence(&hdr->args.seq_args, &hdr->res.seq_res, 0, 0);
}

1
include/linux/nfs_xdr.h
View File

@ -670,6 +670,7 @@ struct nfs_pgio_res {
struct {
unsigned int replen; /* used by read */
int eof; /* used by read */
void * scratch; /* used by read */
};
struct {
struct nfs_writeverf * verf; /* used by write */