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gfs2: Fix freeze consistency check in log_write_header

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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>
This commit is contained in:
Andreas Gruenbacher 2023-12-19 16:49:26 +01:00
parent 4e58543e7d
commit e345b87b0b
2 changed files with 18 additions and 25 deletions
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3
fs/gfs2/log.c
View File

@ -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);

40
fs/gfs2/super.c
View File

@ -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 @@ out:
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,