6.1-stable review patch. If anyone has any objections, please let me know.
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From: Anna Schumaker Anna.Schumaker@Netapp.com
commit 303a78052091c81e9003915c521fdca1c7e117af upstream.
I found that the read code might send multiple requests using the same nfs_pgio_header, but nfs4_proc_read_setup() is only called once. This is how we ended up occasionally double-freeing the scratch buffer, but also means we set a NULL pointer but non-zero length to the xdr scratch buffer. This results in an oops the first time decoding needs to copy something to scratch, which frequently happens when decoding READ_PLUS hole segments.
I fix this by moving scratch handling into the pageio read code. I provide a function to allocate scratch space for decoding read replies, and free the scratch buffer when the nfs_pgio_header is freed.
Fixes: fbd2a05f29a9 (NFSv4.2: Rework scratch handling for READ_PLUS) Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/nfs/internal.h | 1 + fs/nfs/nfs42.h | 1 + fs/nfs/nfs42xdr.c | 2 +- fs/nfs/nfs4proc.c | 13 +------------ fs/nfs/read.c | 10 ++++++++++ 5 files changed, 14 insertions(+), 13 deletions(-)
--- a/fs/nfs/internal.h +++ b/fs/nfs/internal.h @@ -484,6 +484,7 @@ struct nfs_pgio_completion_ops; extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode, bool force_mds, const struct nfs_pgio_completion_ops *compl_ops); +extern bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size); extern void nfs_read_prepare(struct rpc_task *task, void *calldata); extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
--- a/fs/nfs/nfs42.h +++ b/fs/nfs/nfs42.h @@ -13,6 +13,7 @@ * more? Need to consider not to pre-alloc too much for a compound. */ #define PNFS_LAYOUTSTATS_MAXDEV (4) +#define READ_PLUS_SCRATCH_SIZE (16)
/* nfs4.2proc.c */ #ifdef CONFIG_NFS_V4_2 --- a/fs/nfs/nfs42xdr.c +++ b/fs/nfs/nfs42xdr.c @@ -1351,7 +1351,7 @@ static int nfs4_xdr_dec_read_plus(struct struct compound_hdr hdr; int status;
- xdr_set_scratch_buffer(xdr, res->scratch, sizeof(res->scratch)); + xdr_set_scratch_buffer(xdr, res->scratch, READ_PLUS_SCRATCH_SIZE);
status = decode_compound_hdr(xdr, &hdr); if (status) --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -5444,18 +5444,8 @@ static bool nfs4_read_plus_not_supported return false; }
-static inline void nfs4_read_plus_scratch_free(struct nfs_pgio_header *hdr) -{ - if (hdr->res.scratch) { - kfree(hdr->res.scratch); - hdr->res.scratch = NULL; - } -} - static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr) { - nfs4_read_plus_scratch_free(hdr); - if (!nfs4_sequence_done(task, &hdr->res.seq_res)) return -EAGAIN; if (nfs4_read_stateid_changed(task, &hdr->args)) @@ -5475,8 +5465,7 @@ static bool nfs42_read_plus_support(stru /* Note: We don't use READ_PLUS with pNFS yet */ 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 nfs_read_alloc_scratch(hdr, READ_PLUS_SCRATCH_SIZE); } return false; } --- a/fs/nfs/read.c +++ b/fs/nfs/read.c @@ -47,6 +47,8 @@ static struct nfs_pgio_header *nfs_readh
static void nfs_readhdr_free(struct nfs_pgio_header *rhdr) { + if (rhdr->res.scratch != NULL) + kfree(rhdr->res.scratch); kmem_cache_free(nfs_rdata_cachep, rhdr); }
@@ -109,6 +111,14 @@ void nfs_pageio_reset_read_mds(struct nf } EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
+bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size) +{ + WARN_ON(hdr->res.scratch != NULL); + hdr->res.scratch = kmalloc(size, GFP_KERNEL); + return hdr->res.scratch != NULL; +} +EXPORT_SYMBOL_GPL(nfs_read_alloc_scratch); + static void nfs_readpage_release(struct nfs_page *req, int error) { struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);