[PATCH] netfs: Fix missing xas_retry() calls in xarray iteration

[PATCH] netfs: Fix missing xas_retry() calls in xarray iteration

[Anthony Brennan]

commit 59d0d52c30d4991ac4b329f049cc37118e00f5b0 upstream

Stops kernel from crashing when encountering an XAS retry entry. Patch modified
from upstream to work with pages instead of folios, and omits fixes to "dodgy
maths" as unrelated to fixing the crash.

Signed-off-by: Anthony Brennan <a2brenna@hatguy.io>
---
 fs/netfs/read_helper.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 242f8bcb34a4..4de15555bceb 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -248,6 +248,9 @@ static void netfs_rreq_unmark_after_write(struct netfs_read_request *rreq,
 		XA_STATE(xas, &rreq->mapping->i_pages, subreq->start / PAGE_SIZE);
 
 		xas_for_each(&xas, page, (subreq->start + subreq->len - 1) / PAGE_SIZE) {
+			if(xas_retry(&xas, page))
+				continue;
+
 			/* We might have multiple writes from the same huge
 			 * page, but we mustn't unlock a page more than once.
 			 */
@@ -403,6 +406,9 @@ static void netfs_rreq_unlock(struct netfs_read_request *rreq)
 		unsigned int pgend = pgpos + thp_size(page);
 		bool pg_failed = false;
 
+		if(xas_retry(&xas, page))
+			continue;
+
 		for (;;) {
 			if (!subreq) {
 				pg_failed = true;
-- 
2.30.2

RE: [PATCH] netfs: Fix missing xas_retry() calls in xarray iteration

[David Laight]

From: Anthony Brennan
> Sent: 22 December 2023 00:15
> 
> commit 59d0d52c30d4991ac4b329f049cc37118e00f5b0 upstream
> 
> Stops kernel from crashing when encountering an XAS retry entry. Patch modified
> from upstream to work with pages instead of folios, and omits fixes to "dodgy
> maths" as unrelated to fixing the crash.
> 
> Signed-off-by: Anthony Brennan <a2brenna@hatguy.io>
> ---
>  fs/netfs/read_helper.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
> index 242f8bcb34a4..4de15555bceb 100644
> --- a/fs/netfs/read_helper.c
> +++ b/fs/netfs/read_helper.c
> @@ -248,6 +248,9 @@ static void netfs_rreq_unmark_after_write(struct netfs_read_request *rreq,
>  		XA_STATE(xas, &rreq->mapping->i_pages, subreq->start / PAGE_SIZE);
> 
>  		xas_for_each(&xas, page, (subreq->start + subreq->len - 1) / PAGE_SIZE) {
> +			if(xas_retry(&xas, page))

'if' is not a function.

> +				continue;
> +
>  			/* We might have multiple writes from the same huge
>  			 * page, but we mustn't unlock a page more than once.
>  			 */
> @@ -403,6 +406,9 @@ static void netfs_rreq_unlock(struct netfs_read_request *rreq)
>  		unsigned int pgend = pgpos + thp_size(page);
>  		bool pg_failed = false;
> 
> +		if(xas_retry(&xas, page))
> +			continue;
> +
>  		for (;;) {
>  			if (!subreq) {
>  				pg_failed = true;
> --
> 2.30.2

-
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