From patchwork Fri Feb 1 14:32:51 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Foster X-Patchwork-Id: 10792835 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4579C13BF for ; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 367D73222B for ; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2B05632235; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0C87F3222B for ; Fri, 1 Feb 2019 14:32:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726172AbfBAOc5 (ORCPT ); Fri, 1 Feb 2019 09:32:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46976 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726972AbfBAOc5 (ORCPT ); Fri, 1 Feb 2019 09:32:57 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4E7805D61C for ; Fri, 1 Feb 2019 14:32:57 +0000 (UTC) Received: from bfoster.bos.redhat.com (dhcp-41-66.bos.redhat.com [10.18.41.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id 077995D982 for ; Fri, 1 Feb 2019 14:32:56 +0000 (UTC) From: Brian Foster To: linux-xfs@vger.kernel.org Subject: [PATCH v4 1/6] xfs: eof trim writeback mapping as soon as it is cached Date: Fri, 1 Feb 2019 09:32:51 -0500 Message-Id: <20190201143256.43232-2-bfoster@redhat.com> In-Reply-To: <20190201143256.43232-1-bfoster@redhat.com> References: <20190201143256.43232-1-bfoster@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 01 Feb 2019 14:32:57 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The cached writeback mapping is EOF trimmed to try and avoid races between post-eof block management and writeback that result in sending cached data to a stale location. The cached mapping is currently trimmed on the validation check, which leaves a race window between the time the mapping is cached and when it is trimmed against the current inode size. For example, if a new mapping is cached by delalloc conversion on a blocksize == page size fs, we could cycle various locks, perform memory allocations, etc. in the writeback codepath before the associated mapping is eventually trimmed to i_size. This leaves enough time for a post-eof truncate and file append before the cached mapping is trimmed. The former event essentially invalidates a range of the cached mapping and the latter bumps the inode size such the trim on the next writepage event won't trim all of the invalid blocks. fstest generic/464 reproduces this scenario occasionally and causes a lost writeback and stale delalloc blocks warning on inode inactivation. To work around this problem, trim the cached writeback mapping as soon as it is cached in addition to on subsequent validation checks. This is a minor tweak to tighten the race window as much as possible until a proper invalidation mechanism is available. Fixes: 40214d128e07 ("xfs: trim writepage mapping to within eof") Cc: # v4.14+ Signed-off-by: Brian Foster Reviewed-by: Allison Henderson Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_aops.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 338b9d9984e0..d9048bcea49c 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -449,6 +449,7 @@ xfs_map_blocks( } wpc->imap = imap; + xfs_trim_extent_eof(&wpc->imap, ip); trace_xfs_map_blocks_found(ip, offset, count, wpc->io_type, &imap); return 0; allocate_blocks: @@ -459,6 +460,7 @@ xfs_map_blocks( ASSERT(whichfork == XFS_COW_FORK || cow_fsb == NULLFILEOFF || imap.br_startoff + imap.br_blockcount <= cow_fsb); wpc->imap = imap; + xfs_trim_extent_eof(&wpc->imap, ip); trace_xfs_map_blocks_alloc(ip, offset, count, wpc->io_type, &imap); return 0; } From patchwork Fri Feb 1 14:32:52 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Foster X-Patchwork-Id: 10792837 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D23466C2 for ; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BC03332229 for ; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AF71C32233; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ACDED32229 for ; Fri, 1 Feb 2019 14:32:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727338AbfBAOc6 (ORCPT ); Fri, 1 Feb 2019 09:32:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46982 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726972AbfBAOc5 (ORCPT ); Fri, 1 Feb 2019 09:32:57 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B425D5D61C for ; Fri, 1 Feb 2019 14:32:57 +0000 (UTC) Received: from bfoster.bos.redhat.com (dhcp-41-66.bos.redhat.com [10.18.41.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6C0965D9D1 for ; Fri, 1 Feb 2019 14:32:57 +0000 (UTC) From: Brian Foster To: linux-xfs@vger.kernel.org Subject: [PATCH v4 2/6] xfs: update fork seq counter on data fork changes Date: Fri, 1 Feb 2019 09:32:52 -0500 Message-Id: <20190201143256.43232-3-bfoster@redhat.com> In-Reply-To: <20190201143256.43232-1-bfoster@redhat.com> References: <20190201143256.43232-1-bfoster@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 01 Feb 2019 14:32:57 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The sequence counter in the xfs_ifork structure is only updated on COW forks. This is because the counter is currently only used to optimize out repetitive COW fork checks at writeback time. Tweak the extent code to update the seq counter regardless of the fork type in preparation for using this counter on data forks as well. Signed-off-by: Brian Foster Reviewed-by: Christoph Hellwig Reviewed-by: Allison Henderson --- fs/xfs/libxfs/xfs_iext_tree.c | 13 ++++++------- fs/xfs/libxfs/xfs_inode_fork.h | 2 +- 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c index 771dd072015d..bc690f2409fa 100644 --- a/fs/xfs/libxfs/xfs_iext_tree.c +++ b/fs/xfs/libxfs/xfs_iext_tree.c @@ -614,16 +614,15 @@ xfs_iext_realloc_root( } /* - * Increment the sequence counter if we are on a COW fork. This allows - * the writeback code to skip looking for a COW extent if the COW fork - * hasn't changed. We use WRITE_ONCE here to ensure the update to the - * sequence counter is seen before the modifications to the extent - * tree itself take effect. + * Increment the sequence counter on extent tree changes. If we are on a COW + * fork, this allows the writeback code to skip looking for a COW extent if the + * COW fork hasn't changed. We use WRITE_ONCE here to ensure the update to the + * sequence counter is seen before the modifications to the extent tree itself + * take effect. */ static inline void xfs_iext_inc_seq(struct xfs_ifork *ifp, int state) { - if (state & BMAP_COWFORK) - WRITE_ONCE(ifp->if_seq, READ_ONCE(ifp->if_seq) + 1); + WRITE_ONCE(ifp->if_seq, READ_ONCE(ifp->if_seq) + 1); } void diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h index 60361d2d74a1..00c62ce170d0 100644 --- a/fs/xfs/libxfs/xfs_inode_fork.h +++ b/fs/xfs/libxfs/xfs_inode_fork.h @@ -14,7 +14,7 @@ struct xfs_dinode; */ struct xfs_ifork { int if_bytes; /* bytes in if_u1 */ - unsigned int if_seq; /* cow fork mod counter */ + unsigned int if_seq; /* fork mod counter */ struct xfs_btree_block *if_broot; /* file's incore btree root */ short if_broot_bytes; /* bytes allocated for root */ unsigned char if_flags; /* per-fork flags */ From patchwork Fri Feb 1 14:32:53 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Foster X-Patchwork-Id: 10792839 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 793DB17E9 for ; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5CB653222B for ; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4F38632238; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 97CEC3222B for ; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728091AbfBAOc7 (ORCPT ); Fri, 1 Feb 2019 09:32:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46990 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726972AbfBAOc6 (ORCPT ); Fri, 1 Feb 2019 09:32:58 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 360A558E29 for ; Fri, 1 Feb 2019 14:32:58 +0000 (UTC) Received: from bfoster.bos.redhat.com (dhcp-41-66.bos.redhat.com [10.18.41.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id D1FE85D962 for ; Fri, 1 Feb 2019 14:32:57 +0000 (UTC) From: Brian Foster To: linux-xfs@vger.kernel.org Subject: [PATCH v4 3/6] xfs: validate writeback mapping using data fork seq counter Date: Fri, 1 Feb 2019 09:32:53 -0500 Message-Id: <20190201143256.43232-4-bfoster@redhat.com> In-Reply-To: <20190201143256.43232-1-bfoster@redhat.com> References: <20190201143256.43232-1-bfoster@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 01 Feb 2019 14:32:58 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The writeback code caches the current extent mapping across multiple xfs_do_writepage() calls to avoid repeated lookups for sequential pages backed by the same extent. This is known to be slightly racy with extent fork changes in certain difficult to reproduce scenarios. The cached extent is trimmed to within EOF to help avoid the most common vector for this problem via speculative preallocation management, but this is a band-aid that does not address the fundamental problem. Now that we have an xfs_ifork sequence counter mechanism used to facilitate COW writeback, we can use the same mechanism to validate consistency between the data fork and cached writeback mappings. On its face, this is somewhat of a big hammer approach because any change to the data fork invalidates any mapping currently cached by a writeback in progress regardless of whether the data fork change overlaps with the range under writeback. In practice, however, the impact of this approach is minimal in most cases. First, data fork changes (delayed allocations) caused by sustained sequential buffered writes are amortized across speculative preallocations. This means that a cached mapping won't be invalidated by each buffered write of a common file copy workload, but rather only on less frequent allocation events. Second, the extent tree is always entirely in-core so an additional lookup of a usable extent mostly costs a shared ilock cycle and in-memory tree lookup. This means that a cached mapping reval is relatively cheap compared to the I/O itself. Third, spurious invalidations don't impact ioend construction. This means that even if the same extent is revalidated multiple times across multiple writepage instances, we still construct and submit the same size ioend (and bio) if the blocks are physically contiguous. Update struct xfs_writepage_ctx with a new field to hold the sequence number of the data fork associated with the currently cached mapping. Check the wpc seqno against the data fork when the mapping is validated and reestablish the mapping whenever the fork has changed since the mapping was cached. This ensures that writeback always uses a valid extent mapping and thus prevents lost writebacks and stale delalloc block problems. Signed-off-by: Brian Foster Reviewed-by: Allison Henderson Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_aops.c | 60 ++++++++++++++++++++++++++++++++++++---------- fs/xfs/xfs_iomap.c | 5 ++-- 2 files changed, 49 insertions(+), 16 deletions(-) diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index d9048bcea49c..5b0256a8a420 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -29,6 +29,7 @@ struct xfs_writepage_ctx { struct xfs_bmbt_irec imap; unsigned int io_type; + unsigned int data_seq; unsigned int cow_seq; struct xfs_ioend *ioend; }; @@ -301,6 +302,42 @@ xfs_end_bio( xfs_destroy_ioend(ioend, blk_status_to_errno(bio->bi_status)); } +/* + * Fast revalidation of the cached writeback mapping. Return true if the current + * mapping is valid, false otherwise. + */ +static bool +xfs_imap_valid( + struct xfs_writepage_ctx *wpc, + struct xfs_inode *ip, + xfs_fileoff_t offset_fsb) +{ + if (offset_fsb < wpc->imap.br_startoff || + offset_fsb >= wpc->imap.br_startoff + wpc->imap.br_blockcount) + return false; + /* + * If this is a COW mapping, it is sufficient to check that the mapping + * covers the offset. Be careful to check this first because the caller + * can revalidate a COW mapping without updating the data seqno. + */ + if (wpc->io_type == XFS_IO_COW) + return true; + + /* + * This is not a COW mapping. Check the sequence number of the data fork + * because concurrent changes could have invalidated the extent. Check + * the COW fork because concurrent changes since the last time we + * checked (and found nothing at this offset) could have added + * overlapping blocks. + */ + if (wpc->data_seq != READ_ONCE(ip->i_df.if_seq)) + return false; + if (xfs_inode_has_cow_data(ip) && + wpc->cow_seq != READ_ONCE(ip->i_cowfp->if_seq)) + return false; + return true; +} + STATIC int xfs_map_blocks( struct xfs_writepage_ctx *wpc, @@ -315,9 +352,11 @@ xfs_map_blocks( struct xfs_bmbt_irec imap; int whichfork = XFS_DATA_FORK; struct xfs_iext_cursor icur; - bool imap_valid; int error = 0; + if (XFS_FORCED_SHUTDOWN(mp)) + return -EIO; + /* * We have to make sure the cached mapping is within EOF to protect * against eofblocks trimming on file release leaving us with a stale @@ -346,17 +385,9 @@ xfs_map_blocks( * against concurrent updates and provides a memory barrier on the way * out that ensures that we always see the current value. */ - imap_valid = offset_fsb >= wpc->imap.br_startoff && - offset_fsb < wpc->imap.br_startoff + wpc->imap.br_blockcount; - if (imap_valid && - (!xfs_inode_has_cow_data(ip) || - wpc->io_type == XFS_IO_COW || - wpc->cow_seq == READ_ONCE(ip->i_cowfp->if_seq))) + if (xfs_imap_valid(wpc, ip, offset_fsb)) return 0; - if (XFS_FORCED_SHUTDOWN(mp)) - return -EIO; - /* * If we don't have a valid map, now it's time to get a new one for this * offset. This will convert delayed allocations (including COW ones) @@ -403,9 +434,10 @@ xfs_map_blocks( } /* - * Map valid and no COW extent in the way? We're done. + * No COW extent overlap. Revalidate now that we may have updated + * ->cow_seq. If the data mapping is still valid, we're done. */ - if (imap_valid) { + if (xfs_imap_valid(wpc, ip, offset_fsb)) { xfs_iunlock(ip, XFS_ILOCK_SHARED); return 0; } @@ -417,6 +449,7 @@ xfs_map_blocks( */ if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap)) imap.br_startoff = end_fsb; /* fake a hole past EOF */ + wpc->data_seq = READ_ONCE(ip->i_df.if_seq); xfs_iunlock(ip, XFS_ILOCK_SHARED); if (imap.br_startoff > offset_fsb) { @@ -454,7 +487,8 @@ xfs_map_blocks( return 0; allocate_blocks: error = xfs_iomap_write_allocate(ip, whichfork, offset, &imap, - &wpc->cow_seq); + whichfork == XFS_COW_FORK ? + &wpc->cow_seq : &wpc->data_seq); if (error) return error; ASSERT(whichfork == XFS_COW_FORK || cow_fsb == NULLFILEOFF || diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 27c93b5f029d..ab69caa685b4 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -681,7 +681,7 @@ xfs_iomap_write_allocate( int whichfork, xfs_off_t offset, xfs_bmbt_irec_t *imap, - unsigned int *cow_seq) + unsigned int *seq) { xfs_mount_t *mp = ip->i_mount; struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork); @@ -797,8 +797,7 @@ xfs_iomap_write_allocate( if (error) goto error0; - if (whichfork == XFS_COW_FORK) - *cow_seq = READ_ONCE(ifp->if_seq); + *seq = READ_ONCE(ifp->if_seq); xfs_iunlock(ip, XFS_ILOCK_EXCL); } From patchwork Fri Feb 1 14:32:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Foster X-Patchwork-Id: 10792841 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8DC436C2 for ; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7841032229 for ; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 695793223B; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E7DE932229 for ; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728493AbfBAOc7 (ORCPT ); Fri, 1 Feb 2019 09:32:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33290 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727586AbfBAOc6 (ORCPT ); Fri, 1 Feb 2019 09:32:58 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8F98FDA322 for ; Fri, 1 Feb 2019 14:32:58 +0000 (UTC) Received: from bfoster.bos.redhat.com (dhcp-41-66.bos.redhat.com [10.18.41.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4451E5D9D1 for ; Fri, 1 Feb 2019 14:32:58 +0000 (UTC) From: Brian Foster To: linux-xfs@vger.kernel.org Subject: [PATCH v4 4/6] xfs: remove superfluous writeback mapping eof trimming Date: Fri, 1 Feb 2019 09:32:54 -0500 Message-Id: <20190201143256.43232-5-bfoster@redhat.com> In-Reply-To: <20190201143256.43232-1-bfoster@redhat.com> References: <20190201143256.43232-1-bfoster@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 01 Feb 2019 14:32:58 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Now that the cached writeback mapping is explicitly invalidated on data fork changes, the EOF trimming band-aid is no longer necessary. Remove xfs_trim_extent_eof() as well since it has no other users. Signed-off-by: Brian Foster Reviewed-by: Christoph Hellwig --- fs/xfs/libxfs/xfs_bmap.c | 11 ----------- fs/xfs/libxfs/xfs_bmap.h | 1 - fs/xfs/xfs_aops.c | 15 --------------- 3 files changed, 27 deletions(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 332eefa2700b..4c73927819c2 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -3685,17 +3685,6 @@ xfs_trim_extent( } } -/* trim extent to within eof */ -void -xfs_trim_extent_eof( - struct xfs_bmbt_irec *irec, - struct xfs_inode *ip) - -{ - xfs_trim_extent(irec, 0, XFS_B_TO_FSB(ip->i_mount, - i_size_read(VFS_I(ip)))); -} - /* * Trim the returned map to the required bounds */ diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h index 09d3ea97cc15..b4ff710d7250 100644 --- a/fs/xfs/libxfs/xfs_bmap.h +++ b/fs/xfs/libxfs/xfs_bmap.h @@ -181,7 +181,6 @@ static inline bool xfs_bmap_is_real_extent(struct xfs_bmbt_irec *irec) void xfs_trim_extent(struct xfs_bmbt_irec *irec, xfs_fileoff_t bno, xfs_filblks_t len); -void xfs_trim_extent_eof(struct xfs_bmbt_irec *, struct xfs_inode *); int xfs_bmap_add_attrfork(struct xfs_inode *ip, int size, int rsvd); int xfs_bmap_set_attrforkoff(struct xfs_inode *ip, int size, int *version); void xfs_bmap_local_to_extents_empty(struct xfs_inode *ip, int whichfork); diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 5b0256a8a420..515532f45beb 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -357,19 +357,6 @@ xfs_map_blocks( if (XFS_FORCED_SHUTDOWN(mp)) return -EIO; - /* - * We have to make sure the cached mapping is within EOF to protect - * against eofblocks trimming on file release leaving us with a stale - * mapping. Otherwise, a page for a subsequent file extending buffered - * write could get picked up by this writeback cycle and written to the - * wrong blocks. - * - * Note that what we really want here is a generic mapping invalidation - * mechanism to protect us from arbitrary extent modifying contexts, not - * just eofblocks. - */ - xfs_trim_extent_eof(&wpc->imap, ip); - /* * COW fork blocks can overlap data fork blocks even if the blocks * aren't shared. COW I/O always takes precedent, so we must always @@ -482,7 +469,6 @@ xfs_map_blocks( } wpc->imap = imap; - xfs_trim_extent_eof(&wpc->imap, ip); trace_xfs_map_blocks_found(ip, offset, count, wpc->io_type, &imap); return 0; allocate_blocks: @@ -494,7 +480,6 @@ xfs_map_blocks( ASSERT(whichfork == XFS_COW_FORK || cow_fsb == NULLFILEOFF || imap.br_startoff + imap.br_blockcount <= cow_fsb); wpc->imap = imap; - xfs_trim_extent_eof(&wpc->imap, ip); trace_xfs_map_blocks_alloc(ip, offset, count, wpc->io_type, &imap); return 0; } From patchwork Fri Feb 1 14:32:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Foster X-Patchwork-Id: 10792843 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E13F513BF for ; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C816032229 for ; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BC52532233; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 21A573222D for ; Fri, 1 Feb 2019 14:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728616AbfBAOc7 (ORCPT ); Fri, 1 Feb 2019 09:32:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33298 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727944AbfBAOc7 (ORCPT ); Fri, 1 Feb 2019 09:32:59 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id ED66E394D3F for ; Fri, 1 Feb 2019 14:32:58 +0000 (UTC) Received: from bfoster.bos.redhat.com (dhcp-41-66.bos.redhat.com [10.18.41.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id A85285D9D1 for ; Fri, 1 Feb 2019 14:32:58 +0000 (UTC) From: Brian Foster To: linux-xfs@vger.kernel.org Subject: [PATCH v4 5/6] xfs: create delalloc bmapi wrapper for full extent allocation Date: Fri, 1 Feb 2019 09:32:55 -0500 Message-Id: <20190201143256.43232-6-bfoster@redhat.com> In-Reply-To: <20190201143256.43232-1-bfoster@redhat.com> References: <20190201143256.43232-1-bfoster@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 01 Feb 2019 14:32:58 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The writeback delalloc conversion code is racy with respect to changes in the currently cached file mapping. This stems from the fact that the bmapi allocation code requires a file range to allocate and the writeback conversion code assumes the range of the currently cached mapping is still valid with respect to the fork. It may not be valid, however, because the ilock is cycled (potentially multiple times) between the time the cached mapping was populated and the delalloc conversion occurs. To facilitate a solution to this problem, create a new xfs_bmapi_delalloc() wrapper to xfs_bmapi_write() that takes a file (FSB) offset and attempts to allocate whatever delalloc extent backs the offset. Use a new bmapi flag to cause xfs_bmapi_write() to set the range based on the extent backing the bno parameter unless bno lands in a hole. If bno does land in a hole, fall back to the current behavior (which may result in an error or quietly skipping holes in the specified range depending on other parameters). This patch does not change behavior. [hch: Rename helper function and tweak interface.] Signed-off-by: Brian Foster Signed-off-by: Christoph Hellwig Reviewed-by: Christoph Hellwig --- fs/xfs/libxfs/xfs_bmap.c | 59 +++++++++++++++++++++++++++++++++++++--- fs/xfs/libxfs/xfs_bmap.h | 4 +++ 2 files changed, 59 insertions(+), 4 deletions(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 4c73927819c2..c629004d9a4c 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -4286,10 +4286,6 @@ xfs_bmapi_write( goto error0; } - n = 0; - end = bno + len; - obno = bno; - if (!xfs_iext_lookup_extent(ip, ifp, bno, &bma.icur, &bma.got)) eof = true; if (!xfs_iext_peek_prev_extent(ifp, &bma.icur, &bma.prev)) @@ -4299,6 +4295,26 @@ xfs_bmapi_write( bma.total = total; bma.datatype = 0; + /* + * The reval flag means the caller wants to allocate the entire delalloc + * extent backing bno where bno may not necessarily match the startoff. + * Now that we've looked up the extent, reset the range to map based on + * the extent in the file. If we're in a hole, this may be an error so + * don't adjust anything. + */ + if ((flags & XFS_BMAPI_REVALRANGE) && + !eof && bno >= bma.got.br_startoff) { + ASSERT(flags & XFS_BMAPI_DELALLOC); + bno = bma.got.br_startoff; + len = bma.got.br_blockcount; +#ifdef DEBUG + orig_bno = bno; + orig_len = len; +#endif + } + n = 0; + end = bno + len; + obno = bno; while (bno < end && n < *nmap) { bool need_alloc = false, wasdelay = false; @@ -4455,6 +4471,41 @@ xfs_bmapi_write( return error; } +/* + * Convert an existing delalloc extent to real blocks based on file offset. This + * attempts to allocate the entire delalloc extent and may require multiple + * invocations to allocate the target offset if a large enough physical extent + * is not available. + */ +int +xfs_bmapi_convert_delalloc( + struct xfs_trans *tp, + struct xfs_inode *ip, + xfs_fileoff_t offset_fsb, + int whichfork, + struct xfs_bmbt_irec *imap) +{ + int flags = XFS_BMAPI_DELALLOC; + int nimaps = 1; + int error; + int total = XFS_EXTENTADD_SPACE_RES(ip->i_mount, + XFS_DATA_FORK); + + if (whichfork == XFS_COW_FORK) + flags |= XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC; + + /* + * The reval flag means to allocate the entire extent; pass a dummy + * length of 1. + */ + flags |= XFS_BMAPI_REVALRANGE; + error = xfs_bmapi_write(tp, ip, offset_fsb, 1, flags, total, imap, + &nimaps); + if (!error && !nimaps) + error = -EFSCORRUPTED; + return error; +} + int xfs_bmapi_remap( struct xfs_trans *tp, diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h index b4ff710d7250..75586d56f7a5 100644 --- a/fs/xfs/libxfs/xfs_bmap.h +++ b/fs/xfs/libxfs/xfs_bmap.h @@ -107,6 +107,8 @@ struct xfs_extent_free_item /* Do not update the rmap btree. Used for reconstructing bmbt from rmapbt. */ #define XFS_BMAPI_NORMAP 0x2000 +#define XFS_BMAPI_REVALRANGE 0x4000 + #define XFS_BMAPI_FLAGS \ { XFS_BMAPI_ENTIRE, "ENTIRE" }, \ { XFS_BMAPI_METADATA, "METADATA" }, \ @@ -227,6 +229,8 @@ int xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork, xfs_fileoff_t off, xfs_filblks_t len, xfs_filblks_t prealloc, struct xfs_bmbt_irec *got, struct xfs_iext_cursor *cur, int eof); +int xfs_bmapi_convert_delalloc(struct xfs_trans *, struct xfs_inode *, + xfs_fileoff_t, int, struct xfs_bmbt_irec *); static inline void xfs_bmap_add_free( From patchwork Fri Feb 1 14:32:56 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Foster X-Patchwork-Id: 10792845 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9DC6013BF for ; Fri, 1 Feb 2019 14:33:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8C28932229 for ; Fri, 1 Feb 2019 14:33:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 802DD32233; Fri, 1 Feb 2019 14:33:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6815232229 for ; Fri, 1 Feb 2019 14:33:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727944AbfBAOdA (ORCPT ); Fri, 1 Feb 2019 09:33:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33306 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727586AbfBAOdA (ORCPT ); Fri, 1 Feb 2019 09:33:00 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 626A5394D34 for ; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) Received: from bfoster.bos.redhat.com (dhcp-41-66.bos.redhat.com [10.18.41.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1AE815D9D1 for ; Fri, 1 Feb 2019 14:32:59 +0000 (UTC) From: Brian Foster To: linux-xfs@vger.kernel.org Subject: [PATCH v4 6/6] xfs: use the latest extent at writeback delalloc conversion time Date: Fri, 1 Feb 2019 09:32:56 -0500 Message-Id: <20190201143256.43232-7-bfoster@redhat.com> In-Reply-To: <20190201143256.43232-1-bfoster@redhat.com> References: <20190201143256.43232-1-bfoster@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 01 Feb 2019 14:32:59 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The writeback delalloc conversion code is racy with respect to changes in the currently cached file mapping outside of the current page. This is because the ilock is cycled between the time the caller originally looked up the mapping and across each real allocation of the provided file range. This code has collected various hacks over the years to help combat the symptoms of these races (i.e., truncate race detection, allocation into hole detection, etc.), but none address the fundamental problem that the imap may not be valid at allocation time. Rather than continue to use race detection hacks, update writeback delalloc conversion to a model that explicitly converts the delalloc extent backing the current file offset being processed. The current file offset is the only block we can trust to remain once the ilock is dropped because any operation that can remove the block (truncate, hole punch, etc.) must flush and discard pagecache pages first. Modify xfs_iomap_write_allocate() to use the xfs_bmapi_delalloc() mechanism to request allocation of the entire delalloc extent backing the current offset instead of assuming the extent passed by the caller is unchanged. Record the range specified by the caller and apply it to the resulting allocated extent so previous checks by the caller for COW fork overlap are not lost. Finally, overload the bmapi delalloc flag with the range reval flag behavior since this is the only use case for both. This ensures that writeback always picks up the correct and current extent associated with the page, regardless of races with other extent modifying operations. If operating on a data fork and the COW overlap state has changed since the ilock was cycled, the caller revalidates against the COW fork sequence number before using the imap for the next block. [hch: Call updated delalloc conversion helper.] Signed-off-by: Brian Foster Signed-off-by: Christoph Hellwig Reviewed-by: Christoph Hellwig --- fs/xfs/libxfs/xfs_bmap.c | 16 ++-- fs/xfs/libxfs/xfs_bmap.h | 2 - fs/xfs/xfs_iomap.c | 170 +++++++++++++-------------------------- 3 files changed, 64 insertions(+), 124 deletions(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index c629004d9a4c..f4a65330a2a9 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -4296,15 +4296,14 @@ xfs_bmapi_write( bma.datatype = 0; /* - * The reval flag means the caller wants to allocate the entire delalloc - * extent backing bno where bno may not necessarily match the startoff. - * Now that we've looked up the extent, reset the range to map based on - * the extent in the file. If we're in a hole, this may be an error so - * don't adjust anything. + * The delalloc flag means the caller wants to allocate the entire + * delalloc extent backing bno where bno may not necessarily match the + * startoff. Now that we've looked up the extent, reset the range to + * map based on the extent in the file. If we're in a hole, this may be + * an error so don't adjust anything. */ - if ((flags & XFS_BMAPI_REVALRANGE) && + if ((flags & XFS_BMAPI_DELALLOC) && !eof && bno >= bma.got.br_startoff) { - ASSERT(flags & XFS_BMAPI_DELALLOC); bno = bma.got.br_startoff; len = bma.got.br_blockcount; #ifdef DEBUG @@ -4495,10 +4494,9 @@ xfs_bmapi_convert_delalloc( flags |= XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC; /* - * The reval flag means to allocate the entire extent; pass a dummy + * The delalloc flag means to allocate the entire extent; pass a dummy * length of 1. */ - flags |= XFS_BMAPI_REVALRANGE; error = xfs_bmapi_write(tp, ip, offset_fsb, 1, flags, total, imap, &nimaps); if (!error && !nimaps) diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h index 75586d56f7a5..4dc7d1a02b35 100644 --- a/fs/xfs/libxfs/xfs_bmap.h +++ b/fs/xfs/libxfs/xfs_bmap.h @@ -107,8 +107,6 @@ struct xfs_extent_free_item /* Do not update the rmap btree. Used for reconstructing bmbt from rmapbt. */ #define XFS_BMAPI_NORMAP 0x2000 -#define XFS_BMAPI_REVALRANGE 0x4000 - #define XFS_BMAPI_FLAGS \ { XFS_BMAPI_ENTIRE, "ENTIRE" }, \ { XFS_BMAPI_METADATA, "METADATA" }, \ diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index ab69caa685b4..6af1d3ec0a9c 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -677,25 +677,19 @@ xfs_file_iomap_begin_delay( */ int xfs_iomap_write_allocate( - xfs_inode_t *ip, - int whichfork, - xfs_off_t offset, - xfs_bmbt_irec_t *imap, - unsigned int *seq) + struct xfs_inode *ip, + int whichfork, + xfs_off_t offset, + struct xfs_bmbt_irec *imap, + unsigned int *seq) { - xfs_mount_t *mp = ip->i_mount; - struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork); - xfs_fileoff_t offset_fsb, last_block; - xfs_fileoff_t end_fsb, map_start_fsb; - xfs_filblks_t count_fsb; - xfs_trans_t *tp; - int nimaps; - int error = 0; - int flags = XFS_BMAPI_DELALLOC; - int nres; - - if (whichfork == XFS_COW_FORK) - flags |= XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC; + struct xfs_mount *mp = ip->i_mount; + struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork); + xfs_fileoff_t offset_fsb; + xfs_fileoff_t map_start_fsb; + xfs_extlen_t map_count_fsb; + struct xfs_trans *tp; + int error = 0; /* * Make sure that the dquots are there. @@ -704,106 +698,60 @@ xfs_iomap_write_allocate( if (error) return error; + /* + * Store the file range the caller is interested in because it encodes + * state such as potential overlap with COW fork blocks. We must trim + * the allocated extent down to this range to maintain consistency with + * what the caller expects. Revalidation of the range itself is the + * responsibility of the caller. + */ offset_fsb = XFS_B_TO_FSBT(mp, offset); - count_fsb = imap->br_blockcount; map_start_fsb = imap->br_startoff; + map_count_fsb = imap->br_blockcount; - XFS_STATS_ADD(mp, xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb)); + XFS_STATS_ADD(mp, xs_xstrat_bytes, + XFS_FSB_TO_B(mp, imap->br_blockcount)); - while (count_fsb != 0) { + while (true) { /* - * Set up a transaction with which to allocate the - * backing store for the file. Do allocations in a - * loop until we get some space in the range we are - * interested in. The other space that might be allocated - * is in the delayed allocation extent on which we sit - * but before our buffer starts. + * Allocate in a loop because it may take several attempts to + * allocate real blocks for a contiguous delalloc extent if free + * space is sufficiently fragmented. Note that space for the + * extent and indirect blocks was reserved when the delalloc + * extent was created so there's no need to do so here. */ - nimaps = 0; - while (nimaps == 0) { - nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK); - /* - * We have already reserved space for the extent and any - * indirect blocks when creating the delalloc extent, - * there is no need to reserve space in this transaction - * again. - */ - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, - 0, XFS_TRANS_RESERVE, &tp); - if (error) - return error; - - xfs_ilock(ip, XFS_ILOCK_EXCL); - xfs_trans_ijoin(tp, ip, 0); - - /* - * it is possible that the extents have changed since - * we did the read call as we dropped the ilock for a - * while. We have to be careful about truncates or hole - * punchs here - we are not allowed to allocate - * non-delalloc blocks here. - * - * The only protection against truncation is the pages - * for the range we are being asked to convert are - * locked and hence a truncate will block on them - * first. - * - * As a result, if we go beyond the range we really - * need and hit an delalloc extent boundary followed by - * a hole while we have excess blocks in the map, we - * will fill the hole incorrectly and overrun the - * transaction reservation. - * - * Using a single map prevents this as we are forced to - * check each map we look for overlap with the desired - * range and abort as soon as we find it. Also, given - * that we only return a single map, having one beyond - * what we can return is probably a bit silly. - * - * We also need to check that we don't go beyond EOF; - * this is a truncate optimisation as a truncate sets - * the new file size before block on the pages we - * currently have locked under writeback. Because they - * are about to be tossed, we don't need to write them - * back.... - */ - nimaps = 1; - end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)); - error = xfs_bmap_last_offset(ip, &last_block, - XFS_DATA_FORK); - if (error) - goto trans_cancel; + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, + XFS_TRANS_RESERVE, &tp); + if (error) + return error; - last_block = XFS_FILEOFF_MAX(last_block, end_fsb); - if ((map_start_fsb + count_fsb) > last_block) { - count_fsb = last_block - map_start_fsb; - if (count_fsb == 0) { - error = -EAGAIN; - goto trans_cancel; - } - } + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); - /* - * From this point onwards we overwrite the imap - * pointer that the caller gave to us. - */ - error = xfs_bmapi_write(tp, ip, map_start_fsb, - count_fsb, flags, nres, imap, - &nimaps); - if (error) - goto trans_cancel; + /* + * ilock was dropped since imap was populated which means it + * might no longer be valid. The current page is held locked so + * nothing could have removed the block backing offset_fsb. + * Attempt to allocate whatever delalloc extent currently backs + * offset_fsb and put the result in the imap pointer from the + * caller. We'll trim it down to the caller's most recently + * validated range before we return. + */ + error = xfs_bmapi_convert_delalloc(tp, ip, offset_fsb, + whichfork, imap); + if (error) + goto trans_cancel; - error = xfs_trans_commit(tp); - if (error) - goto error0; + error = xfs_trans_commit(tp); + if (error) + goto error0; - *seq = READ_ONCE(ifp->if_seq); - xfs_iunlock(ip, XFS_ILOCK_EXCL); - } + *seq = READ_ONCE(ifp->if_seq); + xfs_iunlock(ip, XFS_ILOCK_EXCL); /* - * See if we were able to allocate an extent that - * covers at least part of the callers request + * See if we were able to allocate an extent that covers at + * least part of the callers request. */ if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) return xfs_alert_fsblock_zero(ip, imap); @@ -812,15 +760,11 @@ xfs_iomap_write_allocate( (offset_fsb < (imap->br_startoff + imap->br_blockcount))) { XFS_STATS_INC(mp, xs_xstrat_quick); + xfs_trim_extent(imap, map_start_fsb, map_count_fsb); + ASSERT(offset_fsb >= imap->br_startoff && + offset_fsb < imap->br_startoff + imap->br_blockcount); return 0; } - - /* - * So far we have not mapped the requested part of the - * file, just surrounding data, try again. - */ - count_fsb -= imap->br_blockcount; - map_start_fsb = imap->br_startoff + imap->br_blockcount; } trans_cancel: