diff options
| author | Konstantin Khlebnikov <khlebnikov@yandex-team.ru> | 2020-04-09 11:29:47 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-12-08 08:44:27 +0100 |
| commit | 8c85e455f7c9682d2728e64aaaf36b8c490dfce3 (patch) | |
| tree | 8c4659ef0703ad2c2de52c4b966c5c40c60aeb99 | |
| parent | 157c8056abb5982ebcc2a06f14a8725dec7cc956 (diff) | |
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>
| -rw-r--r-- | fs/overlayfs/super.c | 5 | ||||
| -rw-r--r-- | fs/sync.c | 3 | ||||
| -rw-r--r-- | include/linux/fs.h | 2 |
3 files changed, 7 insertions, 3 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index f5cf0938f298..fcf453f7f4ae 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -263,8 +263,8 @@ static int ovl_sync_fs(struct super_block *sb, int wait) return 0; /* - * If this is a sync(2) call or an emergency sync, all the super blocks - * will be iterated, including upper_sb, so no need to do anything. + * Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC). + * All the super blocks will be iterated, including upper_sb. * * If this is a syncfs(2) call, then we do need to call * sync_filesystem() on upper_sb, but enough if we do it when being @@ -1710,6 +1710,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) sb->s_xattr = ovl_xattr_handlers; sb->s_fs_info = ofs; sb->s_flags |= SB_POSIXACL; + sb->s_iflags |= SB_I_SKIP_SYNC; err = -ENOMEM; root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); diff --git a/fs/sync.c b/fs/sync.c index 4d1ff010bc5a..16c2630ee4bf 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -76,7 +76,8 @@ static void sync_inodes_one_sb(struct super_block *sb, void *arg) static void sync_fs_one_sb(struct super_block *sb, void *arg) { - if (!sb_rdonly(sb) && sb->s_op->sync_fs) + if (!sb_rdonly(sb) && !(sb->s_iflags & SB_I_SKIP_SYNC) && + sb->s_op->sync_fs) sb->s_op->sync_fs(sb, *(int *)arg); } diff --git a/include/linux/fs.h b/include/linux/fs.h index 4b1553f570f2..fbbd7ef7f653 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1404,6 +1404,8 @@ 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 */ |