Commit 941b853d authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

cifs: don't fail writepages on -EAGAIN errors 



If CIFSSMBWrite2 returns -EAGAIN, then the error should be considered
temporary. CIFS should retry the write instead of setting an error on
the mapping and returning.

For WB_SYNC_ALL, just retry the write immediately. In the WB_SYNC_NONE
case, call redirty_page_for_writeback on all of the pages that didn't
get written out and then move on.

Also, fix up the handling of a short write with a successful return
code. MS-CIFS says that 0 bytes_written means ENOSPC or EFBIG. It
doesn't mention what a short, but non-zero write means, so for now
treat it as we would an -EAGAIN return.

Reviewed-by: default avatarSuresh Jayaraman <sjayaraman@suse.de>
Reviewed-by: default avatarPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent 12fed00d

fs/cifs/file.c

+37 −12
Original line number Diff line number Diff line
@@ -1377,6 +1377,7 @@ retry: 
				break;

		}

		if (n_iov) {

retry_write:

			open_file = find_writable_file(CIFS_I(mapping->host),

							false);

			if (!open_file) {
@@ -1389,31 +1390,55 @@ retry: 
						   &bytes_written, iov, n_iov,

						   long_op);

				cifsFileInfo_put(open_file);

				cifs_update_eof(cifsi, offset, bytes_written);

			}



			if (rc || bytes_written < bytes_to_write) {

				cERROR(1, "Write2 ret %d, wrote %d",

					  rc, bytes_written);

				mapping_set_error(mapping, rc);

			} else {

			cFYI(1, "Write2 rc=%d, wrote=%u", rc, bytes_written);



			/*

			 * For now, treat a short write as if nothing got

			 * written. A zero length write however indicates

			 * ENOSPC or EFBIG. We have no way to know which

			 * though, so call it ENOSPC for now. EFBIG would

			 * get translated to AS_EIO anyway.

			 *

			 * FIXME: make it take into account the data that did

			 *	  get written

			 */

			if (rc == 0) {

				if (bytes_written == 0)

					rc = -ENOSPC;

				else if (bytes_written < bytes_to_write)

					rc = -EAGAIN;

			}



			/* retry on data-integrity flush */

			if (wbc->sync_mode == WB_SYNC_ALL && rc == -EAGAIN)

				goto retry_write;



			/* fix the stats and EOF */

			if (bytes_written > 0) {

				cifs_stats_bytes_written(tcon, bytes_written);

				cifs_update_eof(cifsi, offset, bytes_written);

			}



			for (i = 0; i < n_iov; i++) {

				page = pvec.pages[first + i];

				/* Should we also set page error on

				success rc but too little data written? */

				/* BB investigate retry logic on temporary

				server crash cases and how recovery works

				when page marked as error */

				if (rc)

				/* on retryable write error, redirty page */

				if (rc == -EAGAIN)

					redirty_page_for_writepage(wbc, page);

				else if (rc != 0)

					SetPageError(page);

				kunmap(page);

				unlock_page(page);

				end_page_writeback(page);

				page_cache_release(page);

			}



			if (rc != -EAGAIN)

				mapping_set_error(mapping, rc);

			else

				rc = 0;



			if ((wbc->nr_to_write -= n_iov) <= 0)

				done = 1;

			index = next;

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