| From f90469a41b30f89eafd1817efad09c7ff3beaed9 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 29 Jun 2021 13:13:57 -0400 |
| Subject: NFS: Fix fscache read from NFS after cache error |
| |
| From: Dave Wysochanski <dwysocha@redhat.com> |
| |
| [ Upstream commit ba512c1bc3232124567a59a3995c773dc79716e8 ] |
| |
| Earlier commits refactored some NFS read code and removed |
| nfs_readpage_async(), but neglected to properly fixup |
| nfs_readpage_from_fscache_complete(). The code path is |
| only hit when something unusual occurs with the cachefiles |
| backing filesystem, such as an IO error or while a cookie |
| is being invalidated. |
| |
| Mark page with PG_checked if fscache IO completes in error, |
| unlock the page, and let the VM decide to re-issue based on |
| PG_uptodate. When the VM reissues the readpage, PG_checked |
| allows us to skip over fscache and read from the server. |
| |
| Link: https://marc.info/?l=linux-nfs&m=162498209518739 |
| Fixes: 1e83b173b266 ("NFS: Add nfs_pageio_complete_read() and remove nfs_readpage_async()") |
| Signed-off-by: Dave Wysochanski <dwysocha@redhat.com> |
| Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| fs/nfs/fscache.c | 18 +++++++++++++----- |
| fs/nfs/read.c | 5 +++-- |
| 2 files changed, 16 insertions(+), 7 deletions(-) |
| |
| --- a/fs/nfs/fscache.c |
| +++ b/fs/nfs/fscache.c |
| @@ -385,12 +385,15 @@ static void nfs_readpage_from_fscache_co |
| "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n", |
| page, context, error); |
| |
| - /* if the read completes with an error, we just unlock the page and let |
| - * the VM reissue the readpage */ |
| - if (!error) { |
| + /* |
| + * If the read completes with an error, mark the page with PG_checked, |
| + * unlock the page, and let the VM reissue the readpage. |
| + */ |
| + if (!error) |
| SetPageUptodate(page); |
| - unlock_page(page); |
| - } |
| + else |
| + SetPageChecked(page); |
| + unlock_page(page); |
| } |
| |
| /* |
| @@ -405,6 +408,11 @@ int __nfs_readpage_from_fscache(struct n |
| "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n", |
| nfs_i_fscache(inode), page, page->index, page->flags, inode); |
| |
| + if (PageChecked(page)) { |
| + ClearPageChecked(page); |
| + return 1; |
| + } |
| + |
| ret = fscache_read_or_alloc_page(nfs_i_fscache(inode), |
| page, |
| nfs_readpage_from_fscache_complete, |
| --- a/fs/nfs/read.c |
| +++ b/fs/nfs/read.c |
| @@ -363,13 +363,13 @@ int nfs_readpage(struct file *file, stru |
| } else |
| desc.ctx = get_nfs_open_context(nfs_file_open_context(file)); |
| |
| + xchg(&desc.ctx->error, 0); |
| if (!IS_SYNC(inode)) { |
| ret = nfs_readpage_from_fscache(desc.ctx, inode, page); |
| if (ret == 0) |
| - goto out; |
| + goto out_wait; |
| } |
| |
| - xchg(&desc.ctx->error, 0); |
| nfs_pageio_init_read(&desc.pgio, inode, false, |
| &nfs_async_read_completion_ops); |
| |
| @@ -379,6 +379,7 @@ int nfs_readpage(struct file *file, stru |
| |
| nfs_pageio_complete_read(&desc.pgio, inode); |
| ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0; |
| +out_wait: |
| if (!ret) { |
| ret = wait_on_page_locked_killable(page); |
| if (!PageUptodate(page) && !ret) |