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mm: split out a writeout helper from pageout

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Patch series "stop passing a writeback_control to swap/shmem writeout",
v3.

This series was intended to remove the last remaining users of
AOP_WRITEPAGE_ACTIVATE after my other pending patches removed the rest,
but spectacularly failed at that.

But instead it nicely improves the code, and removes two pointers from
struct writeback_control.


This patch (of 6):

Move the code to write back swap / shmem folios into a self-contained
helper to keep prepare for refactoring it.

Link: https://lkml.kernel.org/r/20250610054959.2057526-1-hch@lst.de
Link: https://lkml.kernel.org/r/20250610054959.2057526-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Baolin Wang <baolin.wang@linux.aibaba.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Christoph Hellwig 2025-06-10 07:49:37 +02:00 committed by Andrew Morton
parent 453742ba5b
commit 86c4a94643
1 changed files with 48 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

94
mm/vmscan.c
View File

@ -652,14 +652,55 @@ typedef enum {
PAGE_CLEAN,
} pageout_t;
static pageout_t writeout(struct folio *folio, struct address_space *mapping,
struct swap_iocb **plug, struct list_head *folio_list)
{
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
.nr_to_write = SWAP_CLUSTER_MAX,
.range_start = 0,
.range_end = LLONG_MAX,
.for_reclaim = 1,
.swap_plug = plug,
};
int res;
folio_set_reclaim(folio);
/*
* The large shmem folio can be split if CONFIG_THP_SWAP is not enabled
* or we failed to allocate contiguous swap entries.
*/
if (shmem_mapping(mapping)) {
if (folio_test_large(folio))
wbc.list = folio_list;
res = shmem_writeout(folio, &wbc);
} else {
res = swap_writeout(folio, &wbc);
}
if (res < 0)
handle_write_error(mapping, folio, res);
if (res == AOP_WRITEPAGE_ACTIVATE) {
folio_clear_reclaim(folio);
return PAGE_ACTIVATE;
}
/* synchronous write? */
if (!folio_test_writeback(folio))
folio_clear_reclaim(folio);
trace_mm_vmscan_write_folio(folio);
node_stat_add_folio(folio, NR_VMSCAN_WRITE);
return PAGE_SUCCESS;
}
/*
* pageout is called by shrink_folio_list() for each dirty folio.
*/
static pageout_t pageout(struct folio *folio, struct address_space *mapping,
struct swap_iocb **plug, struct list_head *folio_list)
{
int (*writeout)(struct folio *, struct writeback_control *);
/*
* We no longer attempt to writeback filesystem folios here, other
* than tmpfs/shmem. That's taken care of in page-writeback.
@ -690,51 +731,12 @@ static pageout_t pageout(struct folio *folio, struct address_space *mapping,
}
return PAGE_KEEP;
}
if (shmem_mapping(mapping))
writeout = shmem_writeout;
else if (folio_test_anon(folio))
writeout = swap_writeout;
else
if (!shmem_mapping(mapping) && !folio_test_anon(folio))
return PAGE_ACTIVATE;
if (folio_clear_dirty_for_io(folio)) {
int res;
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
.nr_to_write = SWAP_CLUSTER_MAX,
.range_start = 0,
.range_end = LLONG_MAX,
.for_reclaim = 1,
.swap_plug = plug,
};
/*
* The large shmem folio can be split if CONFIG_THP_SWAP is
* not enabled or contiguous swap entries are failed to
* allocate.
*/
if (shmem_mapping(mapping) && folio_test_large(folio))
wbc.list = folio_list;
folio_set_reclaim(folio);
res = writeout(folio, &wbc);
if (res < 0)
handle_write_error(mapping, folio, res);
if (res == AOP_WRITEPAGE_ACTIVATE) {
folio_clear_reclaim(folio);
return PAGE_ACTIVATE;
}
if (!folio_test_writeback(folio)) {
/* synchronous write? */
folio_clear_reclaim(folio);
}
trace_mm_vmscan_write_folio(folio);
node_stat_add_folio(folio, NR_VMSCAN_WRITE);
return PAGE_SUCCESS;
}
return PAGE_CLEAN;
if (!folio_clear_dirty_for_io(folio))
return PAGE_CLEAN;
return writeout(folio, mapping, plug, folio_list);
}
/*