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bcachefs: Fix __bch2_truncate_page()

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__bch2_truncate_page() will mark some of the blocks in a page as
unallocated. But, if the page is mmapped (and writable), every block in
the page needs to be marked dirty, else those blocks won't be written by
__bch2_writepage().

The solution is to change those userspace mappings to RO, so that we
force bch2_page_mkwrite() to be called again.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2020-10-09 00:09:20 -04:00 committed by Kent Overstreet
parent 61ce38b862
commit 9ba2eb25f0
1 changed files with 7 additions and 0 deletions
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7
fs/bcachefs/fs-io.c
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@ -27,6 +27,7 @@
#include <linux/migrate.h>
#include <linux/mmu_context.h>
#include <linux/pagevec.h>
#include <linux/rmap.h>
#include <linux/sched/signal.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/uio.h>
@ -2160,6 +2161,12 @@ static int __bch2_truncate_page(struct bch_inode_info *inode,
ret = bch2_get_page_disk_reservation(c, inode, page, false);
BUG_ON(ret);
/*
* This removes any writeable userspace mappings; we need to force
* .page_mkwrite to be called again before any mmapped writes, to
* redirty the full page:
*/
page_mkclean(page);
filemap_dirty_folio(mapping, page_folio(page));
unlock:
unlock_page(page);