[PATCH 7/7] mm: remove the for_reclaim field from struct writeback_control

Christoph Hellwig
2025-05-08T05:50:09Z

This field is now only set to one in the i915 gem code that only
calls writeback_iter on it, which ignores the flag. All other
checks are thuse dead code and the field can be removed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 1 -
fs/fuse/file.c | 11 -----------
fs/nfs/write.c | 2 +-
include/linux/writeback.h | 1 -
include/trace/events/btrfs.h | 7 ++-----
include/trace/events/writeback.h | 8 ++------
6 files changed, 5 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index dbb7a78ceea7..7dac121d35a4 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -303,7 +303,6 @@ void __shmem_writeback(size_t size, struct address_space *mapping)
.nr_to_write = SWAP_CLUSTER_MAX,
.range_start = 0,
.range_end = LLONG_MAX,
- .for_reclaim = 1,
};
struct folio *folio = NULL;
int error = 0;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index e203dd4fcc0f..c950317bd3dd 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1902,17 +1902,6 @@ int fuse_write_inode(struct inode *inode, struct writeback_control *wbc)
struct fuse_file *ff;
int err;

- /*
- * Inode is always written before the last reference is dropped and
- * hence this should not be reached from reclaim.
- *
- * Writing back the inode from reclaim can deadlock if the request
- * processing itself needs an allocation. Allocations triggering
- * reclaim while serving a request can't be prevented, because it can
- * involve any number of unrelated userspace processes.
- */
- WARN_ON(wbc->for_reclaim);
-
ff = __fuse_write_file_get(fi);
err = fuse_flush_times(inode, ff);
if (ff)
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 374fc6b34c79..cf1d720b8251 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -720,7 +720,7 @@ int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);

if (!(mntflags & NFS_MOUNT_WRITE_EAGER) || wbc->for_kupdate ||
- wbc->for_background || wbc->for_sync || wbc->for_reclaim) {
+ wbc->for_background || wbc->for_sync) {
ioc = nfs_io_completion_alloc(GFP_KERNEL);
if (ioc)
nfs_io_completion_init(ioc, nfs_io_completion_commit,
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 9e960f2faf79..a2848d731a46 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -59,7 +59,6 @@ struct writeback_control {
unsigned for_kupdate:1; /* A kupdate writeback */
unsigned for_background:1; /* A background writeback */
unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
- unsigned for_reclaim:1; /* Invoked from the page allocator */
unsigned range_cyclic:1; /* range_start is cyclic */
unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
unsigned unpinned_netfs_wb:1; /* Cleared I_PINNING_NETFS_WB */
diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
index bebc252db865..0adc40f5e72b 100644
--- a/include/trace/events/btrfs.h
+++ b/include/trace/events/btrfs.h
@@ -686,7 +686,6 @@ DECLARE_EVENT_CLASS(btrfs__writepage,
__field( loff_t, range_start )
__field( loff_t, range_end )
__field( char, for_kupdate )
- __field( char, for_reclaim )
__field( char, range_cyclic )
__field( unsigned long, writeback_index )
__field( u64, root_objectid )
@@ -700,7 +699,6 @@ DECLARE_EVENT_CLASS(btrfs__writepage,
__entry->range_start = wbc->range_start;
__entry->range_end = wbc->range_end;
__entry->for_kupdate = wbc->for_kupdate;
- __entry->for_reclaim = wbc->for_reclaim;
__entry->range_cyclic = wbc->range_cyclic;
__entry->writeback_index = inode->i_mapping->writeback_index;
__entry->root_objectid = btrfs_root_id(BTRFS_I(inode)->root);
@@ -709,13 +707,12 @@ DECLARE_EVENT_CLASS(btrfs__writepage,
TP_printk_btrfs("root=%llu(%s) ino=%llu page_index=%lu "
"nr_to_write=%ld pages_skipped=%ld range_start=%llu "
"range_end=%llu for_kupdate=%d "
- "for_reclaim=%d range_cyclic=%d writeback_index=%lu",
+ "range_cyclic=%d writeback_index=%lu",
show_root_type(__entry->root_objectid),
__entry->ino, __entry->index,
__entry->nr_to_write, __entry->pages_skipped,
__entry->range_start, __entry->range_end,
- __entry->for_kupdate,
- __entry->for_reclaim, __entry->range_cyclic,
+ __entry->for_kupdate, __entry->range_cyclic,
__entry->writeback_index)
);

diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 0ff388131fc9..1e23919c0da9 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -459,7 +459,6 @@ DECLARE_EVENT_CLASS(wbc_class,
__field(int, sync_mode)
__field(int, for_kupdate)
__field(int, for_background)
- __field(int, for_reclaim)
__field(int, range_cyclic)
__field(long, range_start)
__field(long, range_end)
@@ -473,23 +472,20 @@ DECLARE_EVENT_CLASS(wbc_class,
__entry->sync_mode = wbc->sync_mode;
__entry->for_kupdate = wbc->for_kupdate;
__entry->for_background = wbc->for_background;
- __entry->for_reclaim = wbc->for_reclaim;
__entry->range_cyclic = wbc->range_cyclic;
__entry->range_start = (long)wbc->range_start;
__entry->range_end = (long)wbc->range_end;
__entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc);
),

- TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d "
- "bgrd=%d reclm=%d cyclic=%d "
- "start=0x%lx end=0x%lx cgroup_ino=%lu",
+ TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d bgrd=%d "
+ "cyclic=%d start=0x%lx end=0x%lx cgroup_ino=%lu",
__entry->name,
__entry->nr_to_write,
__entry->pages_skipped,
__entry->sync_mode,
__entry->for_kupdate,
__entry->for_background,
- __entry->for_reclaim,
__entry->range_cyclic,
__entry->range_start,
__entry->range_end,
--
2.47.2