xfs: use current->journal_info for detecting transaction recursion

Because the iomap code using PF_MEMALLOC_NOFS to detect transaction
recursion in XFS is just wrong. Remove it from the iomap code and
replace it with XFS specific internal checks using
current->journal_info instead.

[djwong: This change also realigns the lifetime of NOFS flag changes to
match the incore transaction, instead of the inconsistent scheme we have
now.]

Fixes: 9070733b4e ("xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Dave Chinner 2021-02-23 10:26:06 -08:00 committed by Darrick J. Wong
parent 9febcda6f8
commit 756b1c3433
5 changed files with 60 additions and 26 deletions

View File

@ -1458,13 +1458,6 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
PF_MEMALLOC))
goto redirty;
/*
* Given that we do not allow direct reclaim to call us, we should
* never be called in a recursive filesystem reclaim context.
*/
if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS))
goto redirty;
/*
* Is this page beyond the end of the file?
*

View File

@ -2805,7 +2805,7 @@ xfs_btree_split_worker(
struct xfs_btree_split_args *args = container_of(work,
struct xfs_btree_split_args, work);
unsigned long pflags;
unsigned long new_pflags = PF_MEMALLOC_NOFS;
unsigned long new_pflags = 0;
/*
* we are in a transaction context here, but may also be doing work
@ -2817,12 +2817,20 @@ xfs_btree_split_worker(
new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
current_set_flags_nested(&pflags, new_pflags);
xfs_trans_set_context(args->cur->bc_tp);
args->result = __xfs_btree_split(args->cur, args->level, args->ptrp,
args->key, args->curp, args->stat);
xfs_trans_clear_context(args->cur->bc_tp);
current_restore_flags_nested(&pflags, new_pflags);
/*
* Do not access args after complete() has run here. We don't own args
* and the owner may run and free args before we return here.
*/
complete(args->done);
current_restore_flags_nested(&pflags, new_pflags);
}
/*

View File

@ -62,7 +62,7 @@ xfs_setfilesize_trans_alloc(
* We hand off the transaction to the completion thread now, so
* clear the flag here.
*/
current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
xfs_trans_clear_context(tp);
return 0;
}
@ -125,7 +125,7 @@ xfs_setfilesize_ioend(
* thus we need to mark ourselves as being in a transaction manually.
* Similarly for freeze protection.
*/
current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
xfs_trans_set_context(tp);
__sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS);
/* we abort the update if there was an IO error */
@ -568,6 +568,12 @@ xfs_vm_writepage(
{
struct xfs_writepage_ctx wpc = { };
if (WARN_ON_ONCE(current->journal_info)) {
redirty_page_for_writepage(wbc, page);
unlock_page(page);
return 0;
}
return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops);
}
@ -578,6 +584,13 @@ xfs_vm_writepages(
{
struct xfs_writepage_ctx wpc = { };
/*
* Writing back data in a transaction context can result in recursive
* transactions. This is bad, so issue a warning and get out of here.
*/
if (WARN_ON_ONCE(current->journal_info))
return 0;
xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops);
}

View File

@ -72,6 +72,7 @@ xfs_trans_free(
xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false);
trace_xfs_trans_free(tp, _RET_IP_);
xfs_trans_clear_context(tp);
if (!(tp->t_flags & XFS_TRANS_NO_WRITECOUNT))
sb_end_intwrite(tp->t_mountp->m_super);
xfs_trans_free_dqinfo(tp);
@ -123,7 +124,8 @@ xfs_trans_dup(
ntp->t_rtx_res = tp->t_rtx_res - tp->t_rtx_res_used;
tp->t_rtx_res = tp->t_rtx_res_used;
ntp->t_pflags = tp->t_pflags;
xfs_trans_switch_context(tp, ntp);
/* move deferred ops over to the new tp */
xfs_defer_move(ntp, tp);
@ -157,9 +159,6 @@ xfs_trans_reserve(
int error = 0;
bool rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;
/* Mark this thread as being in a transaction */
current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
/*
* Attempt to reserve the needed disk blocks by decrementing
* the number needed from the number available. This will
@ -167,10 +166,8 @@ xfs_trans_reserve(
*/
if (blocks > 0) {
error = xfs_mod_fdblocks(mp, -((int64_t)blocks), rsvd);
if (error != 0) {
current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
if (error != 0)
return -ENOSPC;
}
tp->t_blk_res += blocks;
}
@ -244,9 +241,6 @@ undo_blocks:
xfs_mod_fdblocks(mp, (int64_t)blocks, rsvd);
tp->t_blk_res = 0;
}
current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
return error;
}
@ -272,6 +266,7 @@ retry:
tp = kmem_cache_zalloc(xfs_trans_zone, GFP_KERNEL | __GFP_NOFAIL);
if (!(flags & XFS_TRANS_NO_WRITECOUNT))
sb_start_intwrite(mp->m_super);
xfs_trans_set_context(tp);
/*
* Zero-reservation ("empty") transactions can't modify anything, so
@ -900,7 +895,6 @@ __xfs_trans_commit(
xfs_log_commit_cil(mp, tp, &commit_lsn, regrant);
current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
xfs_trans_free(tp);
/*
@ -932,7 +926,6 @@ out_unreserve:
xfs_log_ticket_ungrant(mp->m_log, tp->t_ticket);
tp->t_ticket = NULL;
}
current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
xfs_trans_free_items(tp, !!error);
xfs_trans_free(tp);
@ -992,9 +985,6 @@ xfs_trans_cancel(
tp->t_ticket = NULL;
}
/* mark this thread as no longer being in a transaction */
current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
xfs_trans_free_items(tp, dirty);
xfs_trans_free(tp);
}

View File

@ -281,4 +281,34 @@ int xfs_trans_alloc_ichange(struct xfs_inode *ip, struct xfs_dquot *udqp,
struct xfs_dquot *gdqp, struct xfs_dquot *pdqp, bool force,
struct xfs_trans **tpp);
static inline void
xfs_trans_set_context(
struct xfs_trans *tp)
{
ASSERT(current->journal_info == NULL);
tp->t_pflags = memalloc_nofs_save();
current->journal_info = tp;
}
static inline void
xfs_trans_clear_context(
struct xfs_trans *tp)
{
if (current->journal_info == tp) {
memalloc_nofs_restore(tp->t_pflags);
current->journal_info = NULL;
}
}
static inline void
xfs_trans_switch_context(
struct xfs_trans *old_tp,
struct xfs_trans *new_tp)
{
ASSERT(current->journal_info == old_tp);
new_tp->t_pflags = old_tp->t_pflags;
old_tp->t_pflags = 0;
current->journal_info = new_tp;
}
#endif /* __XFS_TRANS_H__ */