From e345b87b0b0444d1c644b0ea15cfb50e88f10b55 Mon Sep 17 00:00:00 2001
From: Andreas Gruenbacher <agruenba@redhat.com>
Date: Tue, 19 Dec 2023 16:49:26 +0100
Subject: [PATCH] gfs2: Fix freeze consistency check in log_write_header
Functions gfs2_freeze_super() and gfs2_thaw_super() are using the
SDF_FROZEN flag to indicate when the filesystem is frozen, synchronized
by sd_freeze_mutex. However, this doesn't prevent writes from happening
between the point of calling thaw_super() and the point where the
SDF_FROZEN flag is cleared, so the following assert can trigger in
log_write_header():
gfs2_assert_withdraw(sdp, !test_bit(SDF_FROZEN, &sdp->sd_flags));
Fix that by checking for sb->s_writers.frozen != SB_FREEZE_COMPLETE in
log_write_header() instead. To make sure that the filesystem-specific
part of freezing happens before sb->s_writers.frozen is set to
SB_FREEZE_COMPLETE, move that code from gfs2_freeze_locally() into
gfs2_freeze_fs() and hook that up to the .freeze_fs operation.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
fs/gfs2/log.c | 3 ++-
fs/gfs2/super.c | 40 ++++++++++++++++------------------------
2 files changed, 18 insertions(+), 25 deletions(-)
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 6b3ba8f7b67a9..8cddf955ebc0c 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -913,8 +913,9 @@ void gfs2_write_log_header(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd,
static void log_write_header(struct gfs2_sbd *sdp, u32 flags)
{
blk_opf_t op_flags = REQ_PREFLUSH | REQ_FUA | REQ_META | REQ_SYNC;
+ struct super_block *sb = sdp->sd_vfs;
- gfs2_assert_withdraw(sdp, !test_bit(SDF_FROZEN, &sdp->sd_flags));
+ gfs2_assert_withdraw(sdp, sb->s_writers.frozen != SB_FREEZE_COMPLETE);
if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags)) {
gfs2_ordered_wait(sdp);
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index ae92ae1203d8f..e5f79466340d2 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -673,28 +673,6 @@ static int gfs2_sync_fs(struct super_block *sb, int wait)
return sdp->sd_log_error;
}
-static int gfs2_freeze_locally(struct gfs2_sbd *sdp)
-{
- struct super_block *sb = sdp->sd_vfs;
- int error;
-
- error = freeze_super(sb, FREEZE_HOLDER_USERSPACE);
- if (error)
- return error;
-
- if (test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags)) {
- gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_FREEZE |
- GFS2_LFC_FREEZE_GO_SYNC);
- if (gfs2_withdrawing_or_withdrawn(sdp)) {
- error = thaw_super(sb, FREEZE_HOLDER_USERSPACE);
- if (error)
- return error;
- return -EIO;
- }
- }
- return 0;
-}
-
static int gfs2_do_thaw(struct gfs2_sbd *sdp)
{
struct super_block *sb = sdp->sd_vfs;
@@ -724,7 +702,7 @@ void gfs2_freeze_func(struct work_struct *work)
if (test_bit(SDF_FROZEN, &sdp->sd_flags))
goto freeze_failed;
- error = gfs2_freeze_locally(sdp);
+ error = freeze_super(sb, FREEZE_HOLDER_USERSPACE);
if (error)
goto freeze_failed;
@@ -765,7 +743,7 @@ static int gfs2_freeze_super(struct super_block *sb, enum freeze_holder who)
}
for (;;) {
- error = gfs2_freeze_locally(sdp);
+ error = freeze_super(sb, FREEZE_HOLDER_USERSPACE);
if (error) {
fs_info(sdp, "GFS2: couldn't freeze filesystem: %d\n",
error);
@@ -801,6 +779,19 @@ static int gfs2_freeze_super(struct super_block *sb, enum freeze_holder who)
return error;
}
+static int gfs2_freeze_fs(struct super_block *sb)
+{
+ struct gfs2_sbd *sdp = sb->s_fs_info;
+
+ if (test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags)) {
+ gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_FREEZE |
+ GFS2_LFC_FREEZE_GO_SYNC);
+ if (gfs2_withdrawing_or_withdrawn(sdp))
+ return -EIO;
+ }
+ return 0;
+}
+
/**
* gfs2_thaw_super - reallow writes to the filesystem
* @sb: the VFS structure for the filesystem
@@ -1599,6 +1590,7 @@ const struct super_operations gfs2_super_ops = {
.put_super = gfs2_put_super,
.sync_fs = gfs2_sync_fs,
.freeze_super = gfs2_freeze_super,
+ .freeze_fs = gfs2_freeze_fs,
.thaw_super = gfs2_thaw_super,
.statfs = gfs2_statfs,
.drop_inode = gfs2_drop_inode,
--
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