deadlock between mm_sem and tx assign in zfs_write() and page fault

[mirror_zfs.git] / module / zfs / zfs_vnops.c

diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 5a2e55eb19afb6bdc0b0f75662396df81dcb1c7a..c866352d765b1555b5f0257df5776a481287078b 100644 (file)
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -675,7 +675,10 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
                xuio = (xuio_t *)uio;
        else
 #endif
-               uio_prefaultpages(MIN(n, max_blksz), uio);
+               if (uio_prefaultpages(MIN(n, max_blksz), uio)) {
+                       ZFS_EXIT(zfsvfs);
+                       return (SET_ERROR(EFAULT));
+               }
 
        /*
         * If in append mode, set the io offset pointer to eof.
@@ -820,8 +823,19 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 
                if (abuf == NULL) {
                        tx_bytes = uio->uio_resid;
+                       uio->uio_fault_disable = B_TRUE;
                        error = dmu_write_uio_dbuf(sa_get_db(zp->z_sa_hdl),
                            uio, nbytes, tx);
+                       if (error == EFAULT) {
+                               dmu_tx_commit(tx);
+                               if (uio_prefaultpages(MIN(n, max_blksz), uio)) {
+                                       break;
+                               }
+                               continue;
+                       } else if (error != 0) {
+                               dmu_tx_commit(tx);
+                               break;
+                       }
                        tx_bytes -= uio->uio_resid;
                } else {
                        tx_bytes = nbytes;
@@ -921,8 +935,12 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
                ASSERT(tx_bytes == nbytes);
                n -= nbytes;
 
-               if (!xuio && n > 0)
-                       uio_prefaultpages(MIN(n, max_blksz), uio);
+               if (!xuio && n > 0) {
+                       if (uio_prefaultpages(MIN(n, max_blksz), uio)) {
+                               error = EFAULT;
+                               break;
+                       }
+               }
        }
 
        zfs_inode_update(zp);