This patch adds support to process read calls passed by io_submit()
asynchronously. It based on the previously introduced async context
that allows to process i/o responses in a separate thread and
return the caller immediately for asynchronous calls.
This improves reading performance of single threaded applications
with increasing of i/o queue depth size.
Signed-off-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
---
fs/cifs/cifsglob.h | 1 +
fs/cifs/file.c | 169 ++++++++++++++++++++++++++++++++++++++++-------------
2 files changed, 131 insertions(+), 39 deletions(-)
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index bb41226..9438c7c 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1140,6 +1140,7 @@ struct cifs_readdata {
struct completion done;
struct cifsFileInfo *cfile;
struct address_space *mapping;
+ struct cifs_aio_ctx *ctx;
__u64 offset;
unsigned int bytes;
unsigned int got_bytes;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 21d4045..9564e2c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2859,6 +2859,7 @@ cifs_uncached_readdata_release(struct kref *refcount)
struct cifs_readdata, refcount);
unsigned int i;
+ kref_put(&rdata->ctx->refcount, cifs_aio_ctx_release);
for (i = 0; i < rdata->nr_pages; i++) {
put_page(rdata->pages[i]);
rdata->pages[i] = NULL;
@@ -2900,6 +2901,8 @@ cifs_readdata_to_iov(struct cifs_readdata *rdata, struct iov_iter *iter)
return remaining ? -EFAULT : 0;
}
+static void collect_uncached_read_data(struct cifs_aio_ctx *ctx);
+
static void
cifs_uncached_readv_complete(struct work_struct *work)
{
@@ -2907,6 +2910,8 @@ cifs_uncached_readv_complete(struct work_struct *work)
struct cifs_readdata, work);
complete(&rdata->done);
+ collect_uncached_read_data(rdata->ctx);
+ /* the below call can possibly free the last ref to aio ctx */
kref_put(&rdata->refcount, cifs_uncached_readdata_release);
}
@@ -2973,7 +2978,8 @@ cifs_uncached_copy_into_pages(struct TCP_Server_Info *server,
static int
cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
- struct cifs_sb_info *cifs_sb, struct list_head *rdata_list)
+ struct cifs_sb_info *cifs_sb, struct list_head *rdata_list,
+ struct cifs_aio_ctx *ctx)
{
struct cifs_readdata *rdata;
unsigned int npages, rsize, credits;
@@ -3020,6 +3026,8 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
rdata->read_into_pages = cifs_uncached_read_into_pages;
rdata->copy_into_pages = cifs_uncached_copy_into_pages;
rdata->credits = credits;
+ rdata->ctx = ctx;
+ kref_get(&ctx->refcount);
if (!rdata->cfile->invalidHandle ||
!(rc = cifs_reopen_file(rdata->cfile, true)))
@@ -3042,50 +3050,37 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
return rc;
}
-ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
+static void
+collect_uncached_read_data(struct cifs_aio_ctx *ctx)
{
- struct file *file = iocb->ki_filp;
- ssize_t rc;
- size_t len;
- ssize_t total_read = 0;
- loff_t offset = iocb->ki_pos;
+ struct cifs_readdata *rdata, *tmp;
+ struct iov_iter *to = &ctx->iter;
struct cifs_sb_info *cifs_sb;
struct cifs_tcon *tcon;
- struct cifsFileInfo *open_file;
- struct cifs_readdata *rdata, *tmp;
- struct list_head rdata_list;
-
- len = iov_iter_count(to);
- if (!len)
- return 0;
+ unsigned int i;
+ int rc;
- INIT_LIST_HEAD(&rdata_list);
- cifs_sb = CIFS_FILE_SB(file);
- open_file = file->private_data;
- tcon = tlink_tcon(open_file->tlink);
+ tcon = tlink_tcon(ctx->cfile->tlink);
+ cifs_sb = CIFS_SB(ctx->cfile->dentry->d_sb);
- if (!tcon->ses->server->ops->async_readv)
- return -ENOSYS;
+ mutex_lock(&ctx->aio_mutex);
- if ((file->f_flags & O_ACCMODE) == O_WRONLY)
- cifs_dbg(FYI, "attempting read on write only file instance\n");
-
- rc = cifs_send_async_read(offset, len, open_file, cifs_sb, &rdata_list);
-
- /* if at least one read request send succeeded, then reset rc */
- if (!list_empty(&rdata_list))
- rc = 0;
+ if (list_empty(&ctx->list)) {
+ mutex_unlock(&ctx->aio_mutex);
+ return;
+ }
- len = iov_iter_count(to);
+ rc = ctx->rc;
/* the loop below should proceed in the order of increasing offsets */
again:
- list_for_each_entry_safe(rdata, tmp, &rdata_list, list) {
+ list_for_each_entry_safe(rdata, tmp, &ctx->list, list) {
if (!rc) {
- /* FIXME: freezable sleep too? */
- rc = wait_for_completion_killable(&rdata->done);
- if (rc)
- rc = -EINTR;
- else if (rdata->result == -EAGAIN) {
+ if (!try_wait_for_completion(&rdata->done)) {
+ mutex_unlock(&ctx->aio_mutex);
+ return;
+ }
+
+ if (rdata->result == -EAGAIN) {
/* resend call if it's a retryable error */
struct list_head tmp_list;
unsigned int got_bytes = rdata->got_bytes;
@@ -3111,9 +3106,9 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
rdata->offset + got_bytes,
rdata->bytes - got_bytes,
rdata->cfile, cifs_sb,
- &tmp_list);
+ &tmp_list, ctx);
- list_splice(&tmp_list, &rdata_list);
+ list_splice(&tmp_list, &ctx->list);
kref_put(&rdata->refcount,
cifs_uncached_readdata_release);
@@ -3131,14 +3126,110 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
kref_put(&rdata->refcount, cifs_uncached_readdata_release);
}
- total_read = len - iov_iter_count(to);
+ for (i = 0; i < ctx->npages; i++) {
+ if (ctx->should_dirty)
+ set_page_dirty(ctx->bv[i].bv_page);
+ put_page(ctx->bv[i].bv_page);
+ }
- cifs_stats_bytes_read(tcon, total_read);
+ ctx->total_len = ctx->len - iov_iter_count(to);
+
+ cifs_stats_bytes_read(tcon, ctx->total_len);
/* mask nodata case */
if (rc == -ENODATA)
rc = 0;
+ ctx->rc = (rc == 0) ? ctx->total_len : rc;
+
+ mutex_unlock(&ctx->aio_mutex);
+
+ if (ctx->iocb && ctx->iocb->ki_complete)
+ ctx->iocb->ki_complete(ctx->iocb, ctx->rc, 0);
+ else
+ complete(&ctx->done);
+}
+
+ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct file *file = iocb->ki_filp;
+ ssize_t rc;
+ size_t len;
+ ssize_t total_read = 0;
+ loff_t offset = iocb->ki_pos;
+ struct cifs_sb_info *cifs_sb;
+ struct cifs_tcon *tcon;
+ struct cifsFileInfo *cfile;
+ struct cifs_aio_ctx *ctx;
+
+ len = iov_iter_count(to);
+ if (!len)
+ return 0;
+
+ cifs_sb = CIFS_FILE_SB(file);
+ cfile = file->private_data;
+ tcon = tlink_tcon(cfile->tlink);
+
+ if (!tcon->ses->server->ops->async_readv)
+ return -ENOSYS;
+
+ if ((file->f_flags & O_ACCMODE) == O_WRONLY)
+ cifs_dbg(FYI, "attempting read on write only file instance\n");
+
+ ctx = cifs_aio_ctx_alloc();
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->cfile = cifsFileInfo_get(cfile);
+
+ if (!is_sync_kiocb(iocb))
+ ctx->iocb = iocb;
+
+ if (to->type & ITER_IOVEC)
+ ctx->should_dirty = true;
+
+ rc = setup_aio_ctx_iter(ctx, to, READ);
+ if (rc) {
+ kref_put(&ctx->refcount, cifs_aio_ctx_release);
+ return rc;
+ }
+
+ len = ctx->len;
+
+ /* grab a lock here due to read response handlers can access ctx */
+ mutex_lock(&ctx->aio_mutex);
+
+ rc = cifs_send_async_read(offset, len, cfile, cifs_sb, &ctx->list, ctx);
+
+ /* if at least one read request send succeeded, then reset rc */
+ if (!list_empty(&ctx->list))
+ rc = 0;
+
+ mutex_unlock(&ctx->aio_mutex);
+
+ if (rc) {
+ kref_put(&ctx->refcount, cifs_aio_ctx_release);
+ return rc;
+ }
+
+ if (!is_sync_kiocb(iocb)) {
+ kref_put(&ctx->refcount, cifs_aio_ctx_release);
+ return -EIOCBQUEUED;
+ }
+
+ rc = wait_for_completion_killable(&ctx->done);
+ if (rc) {
+ mutex_lock(&ctx->aio_mutex);
+ ctx->rc = rc = -EINTR;
+ total_read = ctx->total_len;
+ mutex_unlock(&ctx->aio_mutex);
+ } else {
+ rc = ctx->rc;
+ total_read = ctx->total_len;
+ }
+
+ kref_put(&ctx->refcount, cifs_aio_ctx_release);
+
if (total_read) {
iocb->ki_pos += total_read;
return total_read;
--
2.7.4
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