When a direct I/O write is performed, iomap_dio_rw() invalidates the
part of the page cache which the write is going to before carrying out
the write.  In the odd case, the direct I/O write will be reading from
the same page it is writing to.  gfs2 carries out writes with page
faults disabled, so it should have been obvious that this page
invalidation can cause iomap_dio_rw() to never make any progress.
Currently, gfs2 will end up in an endless retry loop in
gfs2_file_direct_write() instead, though.

Break this endless loop by limiting the number of retries and falling
back to buffered I/O after that.

Also simplify should_fault_in_pages() sightly and add a comment to make
the above case easier to understand.

Reported-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

On corrupt gfs2 file systems the evict code can try to reference the
journal descriptor structure, jdesc, after it has been freed and set to
NULL. The sequence of events is:

init_journal()
...
fail_jindex:
   gfs2_jindex_free(sdp); <------frees journals, sets jdesc = NULL
      if (gfs2_holder_initialized(&ji_gh))
         gfs2_glock_dq_uninit(&ji_gh);
fail:
   iput(sdp->sd_jindex); <--references jdesc in evict_linked_inode
      evict()
         gfs2_evict_inode()
            evict_linked_inode()
               ret = gfs2_trans_begin(sdp, 0, sdp->sd_jdesc->jd_blocks);
<------references the now freed/zeroed sd_jdesc pointer.

The call to gfs2_trans_begin is done because the truncate_inode_pages
call can cause gfs2 events that require a transaction, such as removing
journaled data (jdata) blocks from the journal.

This patch fixes the problem by adding a check for sdp->sd_jdesc to
function gfs2_evict_inode. In theory, this should only happen to corrupt
gfs2 file systems, when gfs2 detects the problem, reports it, then tries
to evict all the system inodes it has read in up to that point.

Reported-by: Yang Lan <lanyang0908@gmail.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Pull gfs2 updates from Andreas Gruenbacher:

 - Fix revoke processing at unmount and on read-only remount

 - Refuse reading in inodes with an impossible indirect block height

 - Various minor cleanups

* tag 'gfs2-v6.3-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: gfs2_ail_empty_gl no log flush on error
  gfs2: Issue message when revokes cannot be written
  gfs2: Perform second log flush in gfs2_make_fs_ro
  gfs2: return errors from gfs2_ail_empty_gl
  gfs2: Move variable assignment behind a null pointer check in inode_go_dump
  gfs2: Use gfs2_holder_initialized for jindex
  gfs2: Eliminate gfs2_trim_blocks
  gfs2: Fix inode height consistency check
  gfs2: Remove ghs[] from gfs2_unlink
  gfs2: Remove ghs[] from gfs2_link
  gfs2: Remove duplicate i_nlink check from gfs2_link()

Before this patch, function gfs2_ail_empty_gl called gfs2_log_flush even
in cases where it encountered an error. It should probably skip the log
flush and leave the file system in an inconsistent state, letting a
subsequent withdraw force the journal to be replayed to reestablish
metadata consistency.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Before this patch, function gfs2_ail_empty_gl would silently return an
error to the caller. This would get silently set into sd_log_error which
would cause a withdraw, but there was no indication why the file system
was withdrawn. This patch adds a fs_err to log the appropriate error
message.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Before this patch, function gfs2_make_fs_ro called gfs2_log_flush once to
finalize the log. However, if there's dirty metadata, log flushes tend
to sync the metadata and formulate revokes. Before this patch, those
revokes may not be written out to the journal immediately, which meant
unresolved glocks could still have revokes in their ail lists. When the
glock worker runs, it tries to transition the glock, but the unresolved
revokes in the ail still need to be written, so it tries to start a
transaction. It's impossible to start a transaction because at that
point, the SDF_JOURNAL_LIVE flag has been cleared by gfs2_make_fs_ro.
That causes the glock worker to fail, unable to write the revokes. The
calling sequence looked something like this:

gfs2_make_fs_ro
   gfs2_log_flush - with GFS2_LOG_HEAD_FLUSH_SHUTDOWN flag set
	if (flags & GFS2_LOG_HEAD_FLUSH_SHUTDOWN)
		clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
...meanwhile...
glock_work_func
   do_xmote
      rgrp_go_sync (or possibly inode_go_sync)
         ...
         gfs2_ail_empty_gl
            __gfs2_trans_begin
               if (unlikely(!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))) {
               ...
                  return -EROFS;

The previous patch in the series ("gfs2: return errors from
gfs2_ail_empty_gl") now causes the transaction error to no longer be
ignored, so it causes a warning from MOST of the xfstests:

WARNING: CPU: 11 PID: X at fs/gfs2/super.c:603 gfs2_put_super [gfs2]

which corresponds to:

WARN_ON(gfs2_withdrawing(sdp));

The withdraw was triggered silently from do_xmote by:

	if (unlikely(sdp->sd_log_error && !gfs2_withdrawn(sdp)))
		gfs2_withdraw_delayed(sdp);

This patch adds a second log_flush to gfs2_make_fs_ro: one to sync the
data and one to sync any outstanding revokes and finalize the journal.
Note that both of these log flushes need to be "special," in other
words, not GFS2_LOG_HEAD_FLUSH_NORMAL.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Before this patch, function gfs2_ail_empty_gl did not return errors it
encountered from __gfs2_trans_begin. Those errors usually came from the
fact that the file system was made read-only, often due to unmount
(but theoretically could be due to -o remount,ro), which prevented
the transaction from starting.

The inability to start a transaction prevented its revokes from being
properly written to the journal for glocks during unmount (and
transition to ro).

That meant glocks could be unlocked without the metadata properly
revoked in the journal. So other nodes could grab the glock thinking
that their lvb values were correct, but in fact corresponded to the
glock without its revokes properly synced. That presented as lvb
mismatch errors.

This patch allows gfs2_ail_empty_gl to return the error properly to
the caller.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Pull acl updates from Christian Brauner:
 "After finishing the introduction of the new posix acl api last cycle
  the generic POSIX ACL xattr handlers are still around in the
  filesystems xattr handlers for two reasons:

   (1) Because a few filesystems rely on the ->list() method of the
       generic POSIX ACL xattr handlers in their ->listxattr() inode
       operation.

   (2) POSIX ACLs are only available if IOP_XATTR is raised. The
       IOP_XATTR flag is raised in inode_init_always() based on whether
       the sb->s_xattr pointer is non-NULL. IOW, the registered xattr
       handlers of the filesystem are used to raise IOP_XATTR. Removing
       the generic POSIX ACL xattr handlers from all filesystems would
       risk regressing filesystems that only implement POSIX ACL support
       and no other xattrs (nfs3 comes to mind).

  This contains the work to decouple POSIX ACLs from the IOP_XATTR flag
  as they don't depend on xattr handlers anymore. So it's now possible
  to remove the generic POSIX ACL xattr handlers from the sb->s_xattr
  list of all filesystems. This is a crucial step as the generic POSIX
  ACL xattr handlers aren't used for POSIX ACLs anymore and POSIX ACLs
  don't depend on the xattr infrastructure anymore.

  Adressing problem (1) will require more long-term work. It would be
  best to get rid of the ->list() method of xattr handlers completely at
  some point.

  For erofs, ext{2,4}, f2fs, jffs2, ocfs2, and reiserfs the nop POSIX
  ACL xattr handler is kept around so they can continue to use
  array-based xattr handler indexing.

  This update does simplify the ->listxattr() implementation of all
  these filesystems however"

* tag 'v6.4/vfs.acl' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  acl: don't depend on IOP_XATTR
  ovl: check for ->listxattr() support
  reiserfs: rework priv inode handling
  fs: rename generic posix acl handlers
  reiserfs: rework ->listxattr() implementation
  fs: simplify ->listxattr() implementation
  fs: drop unused posix acl handlers
  xattr: remove unused argument
  xattr: add listxattr helper
  xattr: simplify listxattr helpers

Since commit 27a2660f1ef9 ("gfs2: Dump nrpages for inodes and their
glocks"), inode_go_dump() computes the address of inode within ip before
checking if ip is NULL.  This isn't a bug by itself, but it can give
rise to bugs later.  Avoid that by checking if ip is NULL first.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Before this patch function init_journal() used a local variable jindex to
keep track of whether it needed to dequeue the jindex holder when errors
were found. It also uselessly set the variable just before returning from
the function. This patch simplifies the code by eliminatinng the local
variable in favor of using function gfs2_holder_initialized.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>