lustre: get rid of messing with iovecs

* switch to ->read_iter/->write_iter
* keep a pointer to iov_iter instead of iov/nr_segs
* do not modify iovecs; use iov_iter_truncate()/iov_iter_advance() and
a new primitive - iov_iter_reexpand() (expand previously truncated
iterator) istead.
* (racy) check for lustre VMAs intersecting with iovecs kept for now as
for_each_iov() loop.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

7 files changed, 46 insertions, 163 deletions

diff --git a/drivers/staging/lustre/lustre/include/lclient.h b/drivers/staging/lustre/lustre/include/lclient.h
index 827209ea6bd0..386a36c00f57 100644
--- a/drivers/staging/lustre/lustre/include/lclient.h
+++ b/drivers/staging/lustre/lustre/include/lclient.h
@@ -82,16 +82,7 @@ struct ccc_io {
         /**
          * I/O vector information to or from which read/write is going.
          */
-        struct iovec *cui_iov;
-        unsigned long cui_nrsegs;
-        /**
-         * Total iov count for left IO.
-         */
-        unsigned long cui_tot_nrsegs;
-        /**
-         * Old length for iov that was truncated partially.
-         */
-        size_t cui_iov_olen;
+        struct iov_iter *cui_iter;
         /**
          * Total size for the left IO.
          */
diff --git a/drivers/staging/lustre/lustre/lclient/lcommon_cl.c b/drivers/staging/lustre/lustre/lclient/lcommon_cl.c
index 6907a16dbbd1..a07d5156bc50 100644
--- a/drivers/staging/lustre/lustre/lclient/lcommon_cl.c
+++ b/drivers/staging/lustre/lustre/lclient/lcommon_cl.c
@@ -721,31 +721,12 @@ int ccc_io_one_lock_index(const struct lu_env *env, struct cl_io *io,
 void ccc_io_update_iov(const struct lu_env *env,
                        struct ccc_io *cio, struct cl_io *io)
 {
-        int i;
         size_t size = io->u.ci_rw.crw_count;
 
-        cio->cui_iov_olen = 0;
-        if (!cl_is_normalio(env, io) || cio->cui_tot_nrsegs == 0)
+        if (!cl_is_normalio(env, io) || cio->cui_iter == NULL)
                 return;
 
-        for (i = 0; i < cio->cui_tot_nrsegs; i++) {
-                struct iovec *iv = &cio->cui_iov[i];
-
-                if (iv->iov_len < size)
-                        size -= iv->iov_len;
-                else {
-                        if (iv->iov_len > size) {
-                                cio->cui_iov_olen = iv->iov_len;
-                                iv->iov_len = size;
-                        }
-                        break;
-                }
-        }
-
-        cio->cui_nrsegs = i + 1;
-        LASSERTF(cio->cui_tot_nrsegs >= cio->cui_nrsegs,
-                 "tot_nrsegs: %lu, nrsegs: %lu\n",
-                 cio->cui_tot_nrsegs, cio->cui_nrsegs);
+        iov_iter_truncate(cio->cui_iter, size);
 }
 
 int ccc_io_one_lock(const struct lu_env *env, struct cl_io *io,
@@ -776,30 +757,7 @@ void ccc_io_advance(const struct lu_env *env,
         if (!cl_is_normalio(env, io))
                 return;
 
-        LASSERT(cio->cui_tot_nrsegs >= cio->cui_nrsegs);
-        LASSERT(cio->cui_tot_count  >= nob);
-
-        cio->cui_iov    += cio->cui_nrsegs;
-        cio->cui_tot_nrsegs -= cio->cui_nrsegs;
-        cio->cui_tot_count  -= nob;
-
-        /* update the iov */
-        if (cio->cui_iov_olen > 0) {
-                struct iovec *iv;
-
-                cio->cui_iov--;
-                cio->cui_tot_nrsegs++;
-                iv = &cio->cui_iov[0];
-                if (io->ci_continue) {
-                        iv->iov_base += iv->iov_len;
-                        LASSERT(cio->cui_iov_olen > iv->iov_len);
-                        iv->iov_len = cio->cui_iov_olen - iv->iov_len;
-                } else {
-                        /* restore the iov_len, in case of restart io. */
-                        iv->iov_len = cio->cui_iov_olen;
-                }
-                cio->cui_iov_olen = 0;
-        }
+        iov_iter_reexpand(cio->cui_iter, cio->cui_tot_count  -= nob);
 }
 
 /**
diff --git a/drivers/staging/lustre/lustre/llite/file.c b/drivers/staging/lustre/lustre/llite/file.c
index 220bd8390a84..3efda2540d29 100644
--- a/drivers/staging/lustre/lustre/llite/file.c
+++ b/drivers/staging/lustre/lustre/llite/file.c
@@ -1105,9 +1105,7 @@ restart:
 
                 switch (vio->cui_io_subtype) {
                 case IO_NORMAL:
-                        cio->cui_iov = args->u.normal.via_iov;
-                        cio->cui_nrsegs = args->u.normal.via_nrsegs;
-                        cio->cui_tot_nrsegs = cio->cui_nrsegs;
+                        cio->cui_iter = args->u.normal.via_iter;
                         cio->cui_iocb = args->u.normal.via_iocb;
                         if ((iot == CIT_WRITE) &&
                             !(cio->cui_fd->fd_flags & LL_FILE_GROUP_LOCKED)) {
@@ -1171,56 +1169,23 @@ out:
         return result;
 }
 
-static ssize_t ll_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
-                                unsigned long nr_segs, loff_t pos)
+static ssize_t ll_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
         struct lu_env      *env;
         struct vvp_io_args *args;
-        size_t        count = 0;
         ssize_t      result;
         int              refcheck;
 
-        count = iov_length(iov, nr_segs);
-
         env = cl_env_get(&refcheck);
         if (IS_ERR(env))
                 return PTR_ERR(env);
 
         args = vvp_env_args(env, IO_NORMAL);
-        args->u.normal.via_iov = (struct iovec *)iov;
-        args->u.normal.via_nrsegs = nr_segs;
+        args->u.normal.via_iter = to;
         args->u.normal.via_iocb = iocb;
 
         result = ll_file_io_generic(env, args, iocb->ki_filp, CIT_READ,
-                                    &iocb->ki_pos, count);
-        cl_env_put(env, &refcheck);
-        return result;
-}
-
-static ssize_t ll_file_read(struct file *file, char *buf, size_t count,
-                            loff_t *ppos)
-{
-        struct lu_env *env;
-        struct iovec  *local_iov;
-        struct kiocb  *kiocb;
-        ssize_t result;
-        int         refcheck;
-
-        env = cl_env_get(&refcheck);
-        if (IS_ERR(env))
-                return PTR_ERR(env);
-
-        local_iov = &vvp_env_info(env)->vti_local_iov;
-        kiocb = &vvp_env_info(env)->vti_kiocb;
-        local_iov->iov_base = (void __user *)buf;
-        local_iov->iov_len = count;
-        init_sync_kiocb(kiocb, file);
-        kiocb->ki_pos = *ppos;
-        kiocb->ki_nbytes = count;
-
-        result = ll_file_aio_read(kiocb, local_iov, 1, kiocb->ki_pos);
-        *ppos = kiocb->ki_pos;
-
+                                    &iocb->ki_pos, iov_iter_count(to));
         cl_env_put(env, &refcheck);
         return result;
 }
@@ -1228,12 +1193,10 @@ static ssize_t ll_file_read(struct file *file, char *buf, size_t count,
 /*
  * Write to a file (through the page cache).
  */
-static ssize_t ll_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
-                                 unsigned long nr_segs, loff_t pos)
+static ssize_t ll_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
         struct lu_env      *env;
         struct vvp_io_args *args;
-        size_t        count = iov_length(iov, nr_segs);
         ssize_t      result;
         int              refcheck;
 
@@ -1242,46 +1205,15 @@ static ssize_t ll_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
                 return PTR_ERR(env);
 
         args = vvp_env_args(env, IO_NORMAL);
-        args->u.normal.via_iov = (struct iovec *)iov;
-        args->u.normal.via_nrsegs = nr_segs;
+        args->u.normal.via_iter = from;
         args->u.normal.via_iocb = iocb;
 
         result = ll_file_io_generic(env, args, iocb->ki_filp, CIT_WRITE,
-                                  &iocb->ki_pos, count);
+                                  &iocb->ki_pos, iov_iter_count(from));
         cl_env_put(env, &refcheck);
         return result;
 }
 
-static ssize_t ll_file_write(struct file *file, const char *buf, size_t count,
-                             loff_t *ppos)
-{
-        struct lu_env *env;
-        struct iovec  *local_iov;
-        struct kiocb  *kiocb;
-        ssize_t result;
-        int         refcheck;
-
-        env = cl_env_get(&refcheck);
-        if (IS_ERR(env))
-                return PTR_ERR(env);
-
-        local_iov = &vvp_env_info(env)->vti_local_iov;
-        kiocb = &vvp_env_info(env)->vti_kiocb;
-        local_iov->iov_base = (void __user *)buf;
-        local_iov->iov_len = count;
-        init_sync_kiocb(kiocb, file);
-        kiocb->ki_pos = *ppos;
-        kiocb->ki_nbytes = count;
-
-        result = ll_file_aio_write(kiocb, local_iov, 1, kiocb->ki_pos);
-        *ppos = kiocb->ki_pos;
-
-        cl_env_put(env, &refcheck);
-        return result;
-}
-
-
-
 /*
  * Send file content (through pagecache) somewhere with helper
  */
@@ -3133,10 +3065,10 @@ int ll_inode_permission(struct inode *inode, int mask)
 
 /* -o localflock - only provides locally consistent flock locks */
 struct file_operations ll_file_operations = {
-        .read      = ll_file_read,
-        .aio_read = ll_file_aio_read,
-        .write    = ll_file_write,
-        .aio_write = ll_file_aio_write,
+        .read      = new_sync_read,
+        .read_iter = ll_file_read_iter,
+        .write    = new_sync_write,
+        .write_iter = ll_file_write_iter,
         .unlocked_ioctl = ll_file_ioctl,
         .open      = ll_file_open,
         .release        = ll_file_release,
@@ -3148,10 +3080,10 @@ struct file_operations ll_file_operations = {
 };
 
 struct file_operations ll_file_operations_flock = {
-        .read      = ll_file_read,
-        .aio_read    = ll_file_aio_read,
-        .write    = ll_file_write,
-        .aio_write   = ll_file_aio_write,
+        .read      = new_sync_read,
+        .read_iter    = ll_file_read_iter,
+        .write    = new_sync_write,
+        .write_iter   = ll_file_write_iter,
         .unlocked_ioctl = ll_file_ioctl,
         .open      = ll_file_open,
         .release        = ll_file_release,
@@ -3166,10 +3098,10 @@ struct file_operations ll_file_operations_flock = {
 
 /* These are for -o noflock - to return ENOSYS on flock calls */
 struct file_operations ll_file_operations_noflock = {
-        .read      = ll_file_read,
-        .aio_read    = ll_file_aio_read,
-        .write    = ll_file_write,
-        .aio_write   = ll_file_aio_write,
+        .read      = new_sync_read,
+        .read_iter    = ll_file_read_iter,
+        .write    = new_sync_write,
+        .write_iter   = ll_file_write_iter,
         .unlocked_ioctl = ll_file_ioctl,
         .open      = ll_file_open,
         .release        = ll_file_release,
diff --git a/drivers/staging/lustre/lustre/llite/llite_internal.h b/drivers/staging/lustre/lustre/llite/llite_internal.h
index 69aba0afca41..fbb8650ead34 100644
--- a/drivers/staging/lustre/lustre/llite/llite_internal.h
+++ b/drivers/staging/lustre/lustre/llite/llite_internal.h
@@ -974,8 +974,7 @@ struct vvp_io_args {
         union {
                 struct {
                         struct kiocb      *via_iocb;
-                        struct iovec      *via_iov;
-                        unsigned long      via_nrsegs;
+                        struct iov_iter   *via_iter;
                 } normal;
                 struct {
                         struct pipe_inode_info  *via_pipe;
diff --git a/drivers/staging/lustre/lustre/llite/rw.c b/drivers/staging/lustre/lustre/llite/rw.c
index 416f7a094a6d..b345dfa599f3 100644
--- a/drivers/staging/lustre/lustre/llite/rw.c
+++ b/drivers/staging/lustre/lustre/llite/rw.c
@@ -157,8 +157,7 @@ static struct ll_cl_context *ll_cl_init(struct file *file,
                 result = cl_io_rw_init(env, io, CIT_WRITE, pos, PAGE_CACHE_SIZE);
                 if (result == 0) {
                         cio->cui_fd = LUSTRE_FPRIVATE(file);
-                        cio->cui_iov = NULL;
-                        cio->cui_nrsegs = 0;
+                        cio->cui_iter = NULL;
                         result = cl_io_iter_init(env, io);
                         if (result == 0) {
                                 result = cl_io_lock(env, io);
diff --git a/drivers/staging/lustre/lustre/llite/vvp_io.c b/drivers/staging/lustre/lustre/llite/vvp_io.c
index c7d70091246e..cfe8c625ae64 100644
--- a/drivers/staging/lustre/lustre/llite/vvp_io.c
+++ b/drivers/staging/lustre/lustre/llite/vvp_io.c
@@ -211,27 +211,26 @@ static int vvp_mmap_locks(const struct lu_env *env,
         struct cl_lock_descr   *descr = &cti->cti_descr;
         ldlm_policy_data_t      policy;
         unsigned long      addr;
-        unsigned long      seg;
         ssize_t          count;
         int                  result;
+        struct iov_iter i;
+        struct iovec iov;
 
         LASSERT(io->ci_type == CIT_READ || io->ci_type == CIT_WRITE);
 
         if (!cl_is_normalio(env, io))
                 return 0;
 
-        if (vio->cui_iov == NULL) /* nfs or loop back device write */
+        if (vio->cui_iter == NULL) /* nfs or loop back device write */
                 return 0;
 
         /* No MM (e.g. NFS)? No vmas too. */
         if (mm == NULL)
                 return 0;
 
-        for (seg = 0; seg < vio->cui_nrsegs; seg++) {
-                const struct iovec *iv = &vio->cui_iov[seg];
-
-                addr = (unsigned long)iv->iov_base;
-                count = iv->iov_len;
+        iov_for_each(iov, i, *(vio->cui_iter)) {
+                addr = (unsigned long)iov.iov_base;
+                count = iov.iov_len;
                 if (count == 0)
                         continue;
 
@@ -527,9 +526,7 @@ static int vvp_io_read_start(const struct lu_env *env,
         switch (vio->cui_io_subtype) {
         case IO_NORMAL:
                 LASSERT(cio->cui_iocb->ki_pos == pos);
-                result = generic_file_aio_read(cio->cui_iocb,
-                                               cio->cui_iov, cio->cui_nrsegs,
-                                               cio->cui_iocb->ki_pos);
+                result = generic_file_read_iter(cio->cui_iocb, cio->cui_iter);
                 break;
         case IO_SPLICE:
                 result = generic_file_splice_read(file, &pos,
@@ -595,12 +592,11 @@ static int vvp_io_write_start(const struct lu_env *env,
 
         CDEBUG(D_VFSTRACE, "write: [%lli, %lli)\n", pos, pos + (long long)cnt);
 
-        if (cio->cui_iov == NULL) /* from a temp io in ll_cl_init(). */
+        if (cio->cui_iter == NULL) /* from a temp io in ll_cl_init(). */
                 result = 0;
         else
-                result = generic_file_aio_write(cio->cui_iocb,
-                                                cio->cui_iov, cio->cui_nrsegs,
-                                                cio->cui_iocb->ki_pos);
+                result = generic_file_write_iter(cio->cui_iocb, cio->cui_iter);
+
         if (result > 0) {
                 if (result < cnt)
                         io->ci_continue = 0;
@@ -1162,10 +1158,9 @@ int vvp_io_init(const struct lu_env *env, struct cl_object *obj,
                  *  results."  -- Single Unix Spec */
                 if (count == 0)
                         result = 1;
-                else {
+                else
                         cio->cui_tot_count = count;
-                        cio->cui_tot_nrsegs = 0;
-                }
+
                 /* for read/write, we store the jobid in the inode, and
                  * it'll be fetched by osc when building RPC.
                  *
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 66012352d333..e8a109a75de1 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -90,6 +90,15 @@ static inline void iov_iter_truncate(struct iov_iter *i, size_t count)
                 i->count = count;
 }
 
+/*
+ * reexpand a previously truncated iterator; count must be no more than how much
+ * we had shrunk it.
+ */
+static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
+{
+        i->count = count;
+}
+
 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
 int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);