[PATCH 2/6] xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS

From: Michal Hocko
Date: Mon Feb 06 2017 - 09:09:37 EST


From: Michal Hocko <mhocko@xxxxxxxx>

xfs has defined PF_FSTRANS to declare a scope GFP_NOFS semantic quite
some time ago. We would like to make this concept more generic and use
it for other filesystems as well. Let's start by giving the flag a
more generic name PF_MEMALLOC_NOFS which is in line with an exiting
PF_MEMALLOC_NOIO already used for the same purpose for GFP_NOIO
contexts. Replace all PF_FSTRANS usage from the xfs code in the first
step before we introduce a full API for it as xfs uses the flag directly
anyway.

This patch doesn't introduce any functional change.

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
fs/xfs/kmem.c | 4 ++--
fs/xfs/kmem.h | 2 +-
fs/xfs/libxfs/xfs_btree.c | 2 +-
fs/xfs/xfs_aops.c | 6 +++---
fs/xfs/xfs_trans.c | 12 ++++++------
include/linux/sched.h | 2 ++
6 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
index 339c696bbc01..a76a05dae96b 100644
--- a/fs/xfs/kmem.c
+++ b/fs/xfs/kmem.c
@@ -80,13 +80,13 @@ kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
* context via PF_MEMALLOC_NOIO to prevent memory reclaim re-entering
* the filesystem here and potentially deadlocking.
*/
- if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
+ if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))
noio_flag = memalloc_noio_save();

lflags = kmem_flags_convert(flags);
ptr = __vmalloc(size, lflags | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);

- if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
+ if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))
memalloc_noio_restore(noio_flag);

return ptr;
diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h
index 689f746224e7..d973dbfc2bfa 100644
--- a/fs/xfs/kmem.h
+++ b/fs/xfs/kmem.h
@@ -50,7 +50,7 @@ kmem_flags_convert(xfs_km_flags_t flags)
lflags = GFP_ATOMIC | __GFP_NOWARN;
} else {
lflags = GFP_KERNEL | __GFP_NOWARN;
- if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
+ if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))
lflags &= ~__GFP_FS;
}

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 21e6a6ab6b9a..a2672ba4dc33 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -2866,7 +2866,7 @@ 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_FSTRANS;
+ unsigned long new_pflags = PF_MEMALLOC_NOFS;

/*
* we are in a transaction context here, but may also be doing work
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 3a4434297697..b3d41c1d67ab 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -189,7 +189,7 @@ 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_FSTRANS);
+ current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
return 0;
}

@@ -252,7 +252,7 @@ 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_FSTRANS);
+ current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
__sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS);

/* we abort the update if there was an IO error */
@@ -1015,7 +1015,7 @@ xfs_do_writepage(
* Given that we do not allow direct reclaim to call us, we should
* never be called while in a filesystem transaction.
*/
- if (WARN_ON_ONCE(current->flags & PF_FSTRANS))
+ if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS))
goto redirty;

/*
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 70f42ea86dfb..f5969c8274fc 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -134,7 +134,7 @@ xfs_trans_reserve(
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_FSTRANS);
+ current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);

/*
* Attempt to reserve the needed disk blocks by decrementing
@@ -144,7 +144,7 @@ xfs_trans_reserve(
if (blocks > 0) {
error = xfs_mod_fdblocks(tp->t_mountp, -((int64_t)blocks), rsvd);
if (error != 0) {
- current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
+ current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
return -ENOSPC;
}
tp->t_blk_res += blocks;
@@ -221,7 +221,7 @@ xfs_trans_reserve(
tp->t_blk_res = 0;
}

- current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
+ current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);

return error;
}
@@ -914,7 +914,7 @@ __xfs_trans_commit(

xfs_log_commit_cil(mp, tp, &commit_lsn, regrant);

- current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
+ current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
xfs_trans_free(tp);

/*
@@ -944,7 +944,7 @@ __xfs_trans_commit(
if (commit_lsn == -1 && !error)
error = -EIO;
}
- current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
+ current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
xfs_trans_free_items(tp, NULLCOMMITLSN, !!error);
xfs_trans_free(tp);

@@ -998,7 +998,7 @@ xfs_trans_cancel(
xfs_log_done(mp, tp->t_ticket, NULL, false);

/* mark this thread as no longer being in a transaction */
- current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
+ current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);

xfs_trans_free_items(tp, NULLCOMMITLSN, dirty);
xfs_trans_free(tp);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9159a1e4e838..5be9818e9bd9 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2312,6 +2312,8 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
#define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezable */
#define PF_SUSPEND_TASK 0x80000000 /* this thread called freeze_processes and should not be frozen */

+#define PF_MEMALLOC_NOFS PF_FSTRANS /* Transition to a more generic GFP_NOFS scope semantic */
+
/*
* Only the _current_ task can read/write to tsk->flags, but other
* tasks can access tsk->flags in readonly mode for example
--
2.11.0