[PATCH] knfsd: nfs4: hold filp while reading or writing

We're trying to read and write from a struct file that we may not hold a
reference to any more (since a close could be processed as soon as we drop the
state lock).

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 12 insertions, 3 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index ac4878ac2213..d71f14517b9c 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -45,6 +45,7 @@
 #include <linux/param.h>
 #include <linux/major.h>
 #include <linux/slab.h>
+#include <linux/file.h>
 
 #include <linux/sunrpc/svc.h>
 #include <linux/nfsd/nfsd.h>
@@ -477,26 +478,27 @@ static inline int
 nfsd4_read(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_read *read)
 {
         int status;
-        struct file *filp = NULL;
 
         /* no need to check permission - this will be done in nfsd_read() */
 
+        read->rd_filp = NULL;
         if (read->rd_offset >= OFFSET_MAX)
                 return nfserr_inval;
 
         nfs4_lock_state();
         /* check stateid */
         if ((status = nfs4_preprocess_stateid_op(current_fh, &read->rd_stateid,
-                                        CHECK_FH | RD_STATE, &filp))) {
+                                CHECK_FH | RD_STATE, &read->rd_filp))) {
                 dprintk("NFSD: nfsd4_read: couldn't process stateid!\n");
                 goto out;
         }
+        if (read->rd_filp)
+                get_file(read->rd_filp);
         status = nfs_ok;
 out:
         nfs4_unlock_state();
         read->rd_rqstp = rqstp;
         read->rd_fhp = current_fh;
-        read->rd_filp = filp;
         return status;
 }
 
@@ -633,6 +635,8 @@ nfsd4_write(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_writ
                 dprintk("NFSD: nfsd4_write: couldn't process stateid!\n");
                 goto out;
         }
+        if (filp)
+                get_file(filp);
         nfs4_unlock_state();
 
         write->wr_bytes_written = write->wr_buflen;
@@ -644,6 +648,8 @@ nfsd4_write(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_writ
         status =  nfsd_write(rqstp, current_fh, filp, write->wr_offset,
                         write->wr_vec, write->wr_vlen, write->wr_buflen,
                         &write->wr_how_written);
+        if (filp)
+                fput(filp);
 
         if (status == nfserr_symlink)
                 status = nfserr_inval;
@@ -932,6 +938,9 @@ encode_op:
                         nfs4_put_stateowner(replay_owner);
                         replay_owner = NULL;
                 }
+                /* XXX Ugh, we need to get rid of this kind of special case: */
+                if (op->opnum == OP_READ && op->u.read.rd_filp)
+                        fput(op->u.read.rd_filp);
         }
 
 out: