diff options
author | 2018-10-31 22:13:09 +0000 | |
---|---|---|
committer | 2018-11-02 14:09:41 -0500 | |
commit | 6e6e2b86c29c6fcfa16ad9fdc7ea32027bea5d73 (patch) | |
tree | 1c1c63c0f8191fe88291fe6de8acd341e68bc608 | |
parent | smb3: missing defines and structs for reparse point handling (diff) | |
download | linux-6e6e2b86c29c6fcfa16ad9fdc7ea32027bea5d73.tar.gz linux-6e6e2b86c29c6fcfa16ad9fdc7ea32027bea5d73.tar.bz2 linux-6e6e2b86c29c6fcfa16ad9fdc7ea32027bea5d73.zip |
CIFS: Add support for direct I/O read
With direct I/O read, we transfer the data directly from transport layer to
the user data buffer.
Change in v3: add support for kernel AIO
Change in v4:
Refactor common read code to __cifs_readv for direct and non-direct I/O.
Retry on direct I/O failure.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
-rw-r--r-- | fs/cifs/cifsfs.h | 1 | ||||
-rw-r--r-- | fs/cifs/cifsglob.h | 5 | ||||
-rw-r--r-- | fs/cifs/file.c | 225 |
3 files changed, 192 insertions, 39 deletions
diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h index 24e265a51874..3abea1a3f20c 100644 --- a/fs/cifs/cifsfs.h +++ b/fs/cifs/cifsfs.h @@ -101,6 +101,7 @@ extern int cifs_open(struct inode *inode, struct file *file); extern int cifs_close(struct inode *inode, struct file *file); extern int cifs_closedir(struct inode *inode, struct file *file); extern ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to); +extern ssize_t cifs_direct_readv(struct kiocb *iocb, struct iov_iter *to); extern ssize_t cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to); extern ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from); extern ssize_t cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from); diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index d7c0443d47a4..38ab0fca49e1 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -1186,6 +1186,11 @@ struct cifs_aio_ctx { unsigned int len; unsigned int total_len; bool should_dirty; + /* + * Indicates if this aio_ctx is for direct_io, + * If yes, iter is a copy of the user passed iov_iter + */ + bool direct_io; }; struct cifs_readdata; diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 542d8828e1d0..1be36076e960 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2979,7 +2979,6 @@ cifs_uncached_readdata_release(struct kref *refcount) 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; } cifs_readdata_release(refcount); } @@ -3106,6 +3105,67 @@ cifs_uncached_copy_into_pages(struct TCP_Server_Info *server, return uncached_fill_pages(server, rdata, iter, iter->count); } +static int cifs_resend_rdata(struct cifs_readdata *rdata, + struct list_head *rdata_list, + struct cifs_aio_ctx *ctx) +{ + int wait_retry = 0; + unsigned int rsize, credits; + int rc; + struct TCP_Server_Info *server = + tlink_tcon(rdata->cfile->tlink)->ses->server; + + /* + * Try to resend this rdata, waiting for credits up to 3 seconds. + * Note: we are attempting to resend the whole rdata not in segments + */ + do { + rc = server->ops->wait_mtu_credits(server, rdata->bytes, + &rsize, &credits); + + if (rc) + break; + + if (rsize < rdata->bytes) { + add_credits_and_wake_if(server, credits, 0); + msleep(1000); + wait_retry++; + } + } while (rsize < rdata->bytes && wait_retry < 3); + + /* + * If we can't find enough credits to send this rdata + * release the rdata and return failure, this will pass + * whatever I/O amount we have finished to VFS. + */ + if (rsize < rdata->bytes) { + rc = -EBUSY; + goto out; + } + + rc = -EAGAIN; + while (rc == -EAGAIN) { + rc = 0; + if (rdata->cfile->invalidHandle) + rc = cifs_reopen_file(rdata->cfile, true); + if (!rc) + rc = server->ops->async_readv(rdata); + } + + if (!rc) { + /* Add to aio pending list */ + list_add_tail(&rdata->list, rdata_list); + return 0; + } + + add_credits_and_wake_if(server, rdata->credits, 0); +out: + kref_put(&rdata->refcount, + cifs_uncached_readdata_release); + + return rc; +} + 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, @@ -3117,6 +3177,9 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file, int rc; pid_t pid; struct TCP_Server_Info *server; + struct page **pagevec; + size_t start; + struct iov_iter direct_iov = ctx->iter; server = tlink_tcon(open_file->tlink)->ses->server; @@ -3125,6 +3188,9 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file, else pid = current->tgid; + if (ctx->direct_io) + iov_iter_advance(&direct_iov, offset - ctx->pos); + do { rc = server->ops->wait_mtu_credits(server, cifs_sb->rsize, &rsize, &credits); @@ -3132,20 +3198,57 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file, break; cur_len = min_t(const size_t, len, rsize); - npages = DIV_ROUND_UP(cur_len, PAGE_SIZE); - /* allocate a readdata struct */ - rdata = cifs_readdata_alloc(npages, + if (ctx->direct_io) { + + cur_len = iov_iter_get_pages_alloc( + &direct_iov, &pagevec, + cur_len, &start); + if (cur_len < 0) { + cifs_dbg(VFS, + "couldn't get user pages (cur_len=%zd)" + " iter type %d" + " iov_offset %zd count %zd\n", + cur_len, direct_iov.type, + direct_iov.iov_offset, + direct_iov.count); + dump_stack(); + break; + } + iov_iter_advance(&direct_iov, cur_len); + + rdata = cifs_readdata_direct_alloc( + pagevec, cifs_uncached_readv_complete); + if (!rdata) { + add_credits_and_wake_if(server, credits, 0); + rc = -ENOMEM; + break; + } + + npages = (cur_len + start + PAGE_SIZE-1) / PAGE_SIZE; + rdata->page_offset = start; + rdata->tailsz = npages > 1 ? + cur_len-(PAGE_SIZE-start)-(npages-2)*PAGE_SIZE : + cur_len; + + } else { + + npages = DIV_ROUND_UP(cur_len, PAGE_SIZE); + /* allocate a readdata struct */ + rdata = cifs_readdata_alloc(npages, cifs_uncached_readv_complete); - if (!rdata) { - add_credits_and_wake_if(server, credits, 0); - rc = -ENOMEM; - break; - } + if (!rdata) { + add_credits_and_wake_if(server, credits, 0); + rc = -ENOMEM; + break; + } - rc = cifs_read_allocate_pages(rdata, npages); - if (rc) - goto error; + rc = cifs_read_allocate_pages(rdata, npages); + if (rc) + goto error; + + rdata->tailsz = PAGE_SIZE; + } rdata->cfile = cifsFileInfo_get(open_file); rdata->nr_pages = npages; @@ -3153,7 +3256,6 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file, rdata->bytes = cur_len; rdata->pid = pid; rdata->pagesz = PAGE_SIZE; - rdata->tailsz = PAGE_SIZE; rdata->read_into_pages = cifs_uncached_read_into_pages; rdata->copy_into_pages = cifs_uncached_copy_into_pages; rdata->credits = credits; @@ -3167,9 +3269,11 @@ error: if (rc) { add_credits_and_wake_if(server, rdata->credits, 0); kref_put(&rdata->refcount, - cifs_uncached_readdata_release); - if (rc == -EAGAIN) + cifs_uncached_readdata_release); + if (rc == -EAGAIN) { + iov_iter_revert(&direct_iov, cur_len); continue; + } break; } @@ -3225,45 +3329,62 @@ again: * reading. */ if (got_bytes && got_bytes < rdata->bytes) { - rc = cifs_readdata_to_iov(rdata, to); + rc = 0; + if (!ctx->direct_io) + rc = cifs_readdata_to_iov(rdata, to); if (rc) { kref_put(&rdata->refcount, - cifs_uncached_readdata_release); + cifs_uncached_readdata_release); continue; } } - rc = cifs_send_async_read( + if (ctx->direct_io) { + /* + * Re-use rdata as this is a + * direct I/O + */ + rc = cifs_resend_rdata( + rdata, + &tmp_list, ctx); + } else { + rc = cifs_send_async_read( rdata->offset + got_bytes, rdata->bytes - got_bytes, rdata->cfile, cifs_sb, &tmp_list, ctx); + kref_put(&rdata->refcount, + cifs_uncached_readdata_release); + } + list_splice(&tmp_list, &ctx->list); - kref_put(&rdata->refcount, - cifs_uncached_readdata_release); goto again; } else if (rdata->result) rc = rdata->result; - else + else if (!ctx->direct_io) rc = cifs_readdata_to_iov(rdata, to); /* if there was a short read -- discard anything left */ if (rdata->got_bytes && rdata->got_bytes < rdata->bytes) rc = -ENODATA; + + ctx->total_len += rdata->got_bytes; } list_del_init(&rdata->list); kref_put(&rdata->refcount, cifs_uncached_readdata_release); } - 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); - } + if (!ctx->direct_io) { + 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); + } - ctx->total_len = ctx->len - iov_iter_count(to); + ctx->total_len = ctx->len - iov_iter_count(to); + } cifs_stats_bytes_read(tcon, ctx->total_len); @@ -3281,18 +3402,28 @@ again: complete(&ctx->done); } -ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to) +static ssize_t __cifs_readv( + struct kiocb *iocb, struct iov_iter *to, bool direct) { - struct file *file = iocb->ki_filp; - ssize_t rc; size_t len; - ssize_t total_read = 0; - loff_t offset = iocb->ki_pos; + struct file *file = iocb->ki_filp; struct cifs_sb_info *cifs_sb; - struct cifs_tcon *tcon; struct cifsFileInfo *cfile; + struct cifs_tcon *tcon; + ssize_t rc, total_read = 0; + loff_t offset = iocb->ki_pos; struct cifs_aio_ctx *ctx; + /* + * iov_iter_get_pages_alloc() doesn't work with ITER_KVEC, + * fall back to data copy read path + * this could be improved by getting pages directly in ITER_KVEC + */ + if (direct && to->type & ITER_KVEC) { + cifs_dbg(FYI, "use non-direct cifs_user_readv for kvec I/O\n"); + direct = false; + } + len = iov_iter_count(to); if (!len) return 0; @@ -3319,14 +3450,20 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to) if (iter_is_iovec(to)) ctx->should_dirty = true; - rc = setup_aio_ctx_iter(ctx, to, READ); - if (rc) { - kref_put(&ctx->refcount, cifs_aio_ctx_release); - return rc; + if (direct) { + ctx->pos = offset; + ctx->direct_io = true; + ctx->iter = *to; + ctx->len = len; + } else { + rc = setup_aio_ctx_iter(ctx, to, READ); + if (rc) { + kref_put(&ctx->refcount, cifs_aio_ctx_release); + return rc; + } + len = ctx->len; } - len = ctx->len; - /* grab a lock here due to read response handlers can access ctx */ mutex_lock(&ctx->aio_mutex); @@ -3368,6 +3505,16 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to) return rc; } +ssize_t cifs_direct_readv(struct kiocb *iocb, struct iov_iter *to) +{ + return __cifs_readv(iocb, to, true); +} + +ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to) +{ + return __cifs_readv(iocb, to, false); +} + ssize_t cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to) { |