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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2020-04-09 11:29:47 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-12-08 10:43:26 +0300
commit410fb31d899a19d3514aa9a8fa8b17bac5f5549a (patch)
tree03017af4a2a6839cfce861bde8497a828a6959ef /include
parent04e3ec9328b6cbdacc4391b328b2bb6c9e535158 (diff)
downloadlinux-410fb31d899a19d3514aa9a8fa8b17bac5f5549a.tar.xz
ovl: skip overlayfs superblocks at global sync
[ Upstream commit 32b1924b210a70dcacdf65abd687c5ef86a67541 ] Stacked filesystems like overlayfs has no own writeback, but they have to forward syncfs() requests to backend for keeping data integrity. During global sync() each overlayfs instance calls method ->sync_fs() for backend although it itself is in global list of superblocks too. As a result one syscall sync() could write one superblock several times and send multiple disk barriers. This patch adds flag SB_I_SKIP_SYNC into sb->sb_iflags to avoid that. Reported-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Stable-dep-of: b836c4d29f27 ("ima: detect changes to the backing overlay file") Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/fs.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 95b8ef09b76c..f89748aac8c3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1351,6 +1351,8 @@ extern int send_sigurg(struct fown_struct *fown);
#define SB_I_IMA_UNVERIFIABLE_SIGNATURE 0x00000020
#define SB_I_UNTRUSTED_MOUNTER 0x00000040
+#define SB_I_SKIP_SYNC 0x00000100 /* Skip superblock at global sync */
+
/* Possible states of 'frozen' field */
enum {
SB_UNFROZEN = 0, /* FS is unfrozen */