The patch titled
splice: fix generic_file_splice_read() race with page invalidation
has been added to the -mm tree. Its filename is
splice-fix-generic_file_splice_read-race-with-page-invalidation.patch
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------------------------------------------------------
Subject: splice: fix generic_file_splice_read() race with page invalidation
From: Miklos Szeredi <mszeredi@xxxxxxx>
If a page was invalidated during splicing from file to a pipe, then
generic_file_splice_read() could return a short or zero count.
This manifested itself in rare I/O errors seen on nfs exported fuse
filesystems. This is because nfsd uses splice_direct_to_actor() to read
files, and fuse uses invalidate_inode_pages2() to invalidate stale data on
open.
Fix by redoing the page find/create if it was found to be truncated
(invalidated).
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/splice.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff -puN fs/splice.c~splice-fix-generic_file_splice_read-race-with-page-invalidation fs/splice.c
--- a/fs/splice.c~splice-fix-generic_file_splice_read-race-with-page-invalidation
+++ a/fs/splice.c
@@ -379,13 +379,22 @@ __generic_file_splice_read(struct file *
lock_page(page);
/*
- * page was truncated, stop here. if this isn't the
- * first page, we'll just complete what we already
- * added
+ * Page was truncated, or invalidated by the
+ * filesystem. Redo the find/create, but this time the
+ * page is kept locked, so there's no chance of another
+ * race with truncate/invalidate.
*/
if (!page->mapping) {
unlock_page(page);
- break;
+ page = find_or_create_page(mapping, index,
+ mapping_gfp_mask(mapping));
+
+ if (!page) {
+ error = -ENOMEM;
+ break;
+ }
+ page_cache_release(pages[page_nr]);
+ pages[page_nr] = page;
}
/*
* page was already under io and is now done, great
_
Patches currently in -mm which might be from mszeredi@xxxxxxx are
git-unprivileged-mounts.patch
splice-fix-generic_file_splice_read-race-with-page-invalidation.patch
lockd-dont-return-eagain-for-a-permanent-error.patch
locks-add-special-return-value-for-asynchronous-locks.patch
locks-cleanup-code-duplication.patch
locks-allow-lock-to-return-file_lock_deferred.patch
fuse-prepare-lookup-for-nfs-export.patch
fuse-add-export-operations.patch
fuse-add-fuse_lookup_name-helper.patch
fuse-nfs-export-special-lookups.patch
fuse-lockd-support.patch
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