From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
linux-afs@lists.infradead.org, linux-btrfs@vger.kernel.org,
linux-ext4@vger.kernel.org, cluster-devel@redhat.com,
linux-mm@kvack.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-nilfs@vger.kernel.org
Subject: Re: [PATCH 7/9] gfs2: handle a NULL folio in gfs2_jhead_process_page
Date: Wed, 18 Jan 2023 16:00:33 +0000 [thread overview]
Message-ID: <Y8gXodKIUneO+XQb@casper.infradead.org> (raw)
In-Reply-To: <20230118094329.9553-8-hch@lst.de>
On Wed, Jan 18, 2023 at 10:43:27AM +0100, Christoph Hellwig wrote:
> filemap_get_folio can return NULL, so exit early for that case.
I'm not sure it can return NULL in this specific case. As I understand
this code, we're scanning the journal looking for the log head. We've
just submitted the bio to read this page. I suppose memory pressure
could theoretically push the page out, but if it does, we're doing the
wrong thing by just returning here; we need to retry reading the page.
Assuming we're not willing to do the work to add that case, I think I'd
rather see the crash in folio_wait_locked() than get data corruption
from failing to find the head of the log.
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/gfs2/lops.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
> index 1902413d5d123e..51d4b610127cdb 100644
> --- a/fs/gfs2/lops.c
> +++ b/fs/gfs2/lops.c
> @@ -472,6 +472,8 @@ static void gfs2_jhead_process_page(struct gfs2_jdesc *jd, unsigned long index,
> struct folio *folio;
>
> folio = filemap_get_folio(jd->jd_inode->i_mapping, index);
> + if (!folio)
> + return;
>
> folio_wait_locked(folio);
> if (folio_test_error(folio))
> --
> 2.39.0
>
WARNING: multiple messages have this Message-ID (diff)
From: Matthew Wilcox <willy@infradead.org>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] [PATCH 7/9] gfs2: handle a NULL folio in gfs2_jhead_process_page
Date: Wed, 18 Jan 2023 16:00:33 +0000 [thread overview]
Message-ID: <Y8gXodKIUneO+XQb@casper.infradead.org> (raw)
In-Reply-To: <20230118094329.9553-8-hch@lst.de>
On Wed, Jan 18, 2023 at 10:43:27AM +0100, Christoph Hellwig wrote:
> filemap_get_folio can return NULL, so exit early for that case.
I'm not sure it can return NULL in this specific case. As I understand
this code, we're scanning the journal looking for the log head. We've
just submitted the bio to read this page. I suppose memory pressure
could theoretically push the page out, but if it does, we're doing the
wrong thing by just returning here; we need to retry reading the page.
Assuming we're not willing to do the work to add that case, I think I'd
rather see the crash in folio_wait_locked() than get data corruption
from failing to find the head of the log.
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/gfs2/lops.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
> index 1902413d5d123e..51d4b610127cdb 100644
> --- a/fs/gfs2/lops.c
> +++ b/fs/gfs2/lops.c
> @@ -472,6 +472,8 @@ static void gfs2_jhead_process_page(struct gfs2_jdesc *jd, unsigned long index,
> struct folio *folio;
>
> folio = filemap_get_folio(jd->jd_inode->i_mapping, index);
> + if (!folio)
> + return;
>
> folio_wait_locked(folio);
> if (folio_test_error(folio))
> --
> 2.39.0
>
WARNING: multiple messages have this Message-ID (diff)
From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-xfs@vger.kernel.org, linux-nilfs@vger.kernel.org,
Hugh Dickins <hughd@google.com>,
cluster-devel@redhat.com, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linux-ext4@vger.kernel.org, linux-afs@lists.infradead.org,
linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 7/9] gfs2: handle a NULL folio in gfs2_jhead_process_page
Date: Wed, 18 Jan 2023 16:00:33 +0000 [thread overview]
Message-ID: <Y8gXodKIUneO+XQb@casper.infradead.org> (raw)
In-Reply-To: <20230118094329.9553-8-hch@lst.de>
On Wed, Jan 18, 2023 at 10:43:27AM +0100, Christoph Hellwig wrote:
> filemap_get_folio can return NULL, so exit early for that case.
I'm not sure it can return NULL in this specific case. As I understand
this code, we're scanning the journal looking for the log head. We've
just submitted the bio to read this page. I suppose memory pressure
could theoretically push the page out, but if it does, we're doing the
wrong thing by just returning here; we need to retry reading the page.
Assuming we're not willing to do the work to add that case, I think I'd
rather see the crash in folio_wait_locked() than get data corruption
from failing to find the head of the log.
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/gfs2/lops.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
> index 1902413d5d123e..51d4b610127cdb 100644
> --- a/fs/gfs2/lops.c
> +++ b/fs/gfs2/lops.c
> @@ -472,6 +472,8 @@ static void gfs2_jhead_process_page(struct gfs2_jdesc *jd, unsigned long index,
> struct folio *folio;
>
> folio = filemap_get_folio(jd->jd_inode->i_mapping, index);
> + if (!folio)
> + return;
>
> folio_wait_locked(folio);
> if (folio_test_error(folio))
> --
> 2.39.0
>
next prev parent reply other threads:[~2023-01-18 16:04 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-18 9:43 return an ERR_PTR from __filemap_get_folio Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 9:43 ` [PATCH 1/9] mm: don't look at xarray value entries in split_huge_pages_in_file Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 13:47 ` Matthew Wilcox
2023-01-18 13:47 ` Matthew Wilcox
2023-01-18 13:47 ` [Cluster-devel] " Matthew Wilcox
2023-01-18 9:43 ` [PATCH 2/9] mm: make mapping_get_entry available outside of filemap.c Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 13:49 ` Matthew Wilcox
2023-01-18 13:49 ` Matthew Wilcox
2023-01-18 13:49 ` [Cluster-devel] " Matthew Wilcox
2023-01-18 9:43 ` [PATCH 3/9] mm: use filemap_get_entry in filemap_get_incore_folio Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 13:49 ` Matthew Wilcox
2023-01-18 13:49 ` Matthew Wilcox
2023-01-18 13:49 ` [Cluster-devel] " Matthew Wilcox
2023-01-18 9:43 ` [PATCH 4/9] shmem: remove shmem_get_partial_folio Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 13:57 ` Brian Foster
2023-01-18 13:57 ` Brian Foster
2023-01-18 13:57 ` [Cluster-devel] " Brian Foster
2023-01-18 16:43 ` Christoph Hellwig
2023-01-18 16:43 ` Christoph Hellwig
2023-01-18 16:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 16:50 ` Brian Foster
2023-01-18 16:50 ` Brian Foster
2023-01-18 16:50 ` [Cluster-devel] " Brian Foster
2023-01-18 9:43 ` [PATCH 5/9] shmem: open code the page cache lookup in shmem_get_folio_gfp Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 9:43 ` [PATCH 6/9] mm: remove FGP_ENTRY Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 9:43 ` [PATCH 7/9] gfs2: handle a NULL folio in gfs2_jhead_process_page Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 16:00 ` Matthew Wilcox [this message]
2023-01-18 16:00 ` Matthew Wilcox
2023-01-18 16:00 ` [Cluster-devel] " Matthew Wilcox
2023-01-18 16:24 ` Andreas Gruenbacher
2023-01-18 16:24 ` Andreas Gruenbacher
2023-01-18 16:24 ` [Cluster-devel] " Andreas Gruenbacher
2023-01-18 16:42 ` Christoph Hellwig
2023-01-18 16:42 ` Christoph Hellwig
2023-01-18 9:43 ` [PATCH 8/9] btrfs: handle a NULL folio in extent_range_redirty_for_io Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 16:08 ` Matthew Wilcox
2023-01-18 16:08 ` Matthew Wilcox
2023-01-18 16:08 ` [Cluster-devel] " Matthew Wilcox
2023-01-18 16:42 ` Christoph Hellwig
2023-01-18 16:42 ` Christoph Hellwig
2023-01-18 16:42 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 9:43 ` [PATCH 9/9] mm: return an ERR_PTR from __filemap_get_folio Christoph Hellwig
2023-01-18 9:43 ` Christoph Hellwig
2023-01-18 9:43 ` [Cluster-devel] " Christoph Hellwig
2023-01-18 12:39 ` Ryusuke Konishi
2023-01-18 12:39 ` Ryusuke Konishi
2023-01-18 12:39 ` [Cluster-devel] " Ryusuke Konishi
2023-01-18 16:42 ` Christoph Hellwig
2023-01-18 16:42 ` Christoph Hellwig
2023-01-18 16:42 ` [Cluster-devel] " Christoph Hellwig
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