mm: migrate: lock buffers before migrate_page_move_mapping()
Lock buffers before calling into migrate_page_move_mapping() so that that function doesn't have to know about buffers (which is somewhat unexpected anyway) and all the buffer head logic is in buffer_migrate_page(). Link: http://lkml.kernel.org/r/20181211172143.7358-3-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>hifive-unleashed-5.1
parent
0b3901b38d
commit
cc4f11e69f
39
mm/migrate.c
39
mm/migrate.c
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@ -486,20 +486,6 @@ int migrate_page_move_mapping(struct address_space *mapping,
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return -EAGAIN;
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return -EAGAIN;
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}
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}
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/*
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* In the async migration case of moving a page with buffers, lock the
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* buffers using trylock before the mapping is moved. If the mapping
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* was moved, we later failed to lock the buffers and could not move
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* the mapping back due to an elevated page count, we would have to
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* block waiting on other references to be dropped.
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*/
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if (mode == MIGRATE_ASYNC && head &&
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!buffer_migrate_lock_buffers(head, mode)) {
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page_ref_unfreeze(page, expected_count);
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xas_unlock_irq(&xas);
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return -EAGAIN;
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}
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/*
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/*
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* Now we know that no one else is looking at the page:
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* Now we know that no one else is looking at the page:
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* no turning back from here.
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* no turning back from here.
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@ -775,24 +761,23 @@ int buffer_migrate_page(struct address_space *mapping,
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{
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{
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struct buffer_head *bh, *head;
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struct buffer_head *bh, *head;
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int rc;
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int rc;
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int expected_count;
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if (!page_has_buffers(page))
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if (!page_has_buffers(page))
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return migrate_page(mapping, newpage, page, mode);
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return migrate_page(mapping, newpage, page, mode);
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/* Check whether page does not have extra refs before we do more work */
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expected_count = expected_page_refs(page);
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if (page_count(page) != expected_count)
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return -EAGAIN;
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head = page_buffers(page);
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head = page_buffers(page);
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if (!buffer_migrate_lock_buffers(head, mode))
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return -EAGAIN;
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rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0);
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rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
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if (rc != MIGRATEPAGE_SUCCESS)
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if (rc != MIGRATEPAGE_SUCCESS)
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return rc;
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goto unlock_buffers;
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/*
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* In the async case, migrate_page_move_mapping locked the buffers
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* with an IRQ-safe spinlock held. In the sync case, the buffers
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* need to be locked now
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*/
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if (mode != MIGRATE_ASYNC)
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BUG_ON(!buffer_migrate_lock_buffers(head, mode));
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ClearPagePrivate(page);
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ClearPagePrivate(page);
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set_page_private(newpage, page_private(page));
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set_page_private(newpage, page_private(page));
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@ -814,6 +799,8 @@ int buffer_migrate_page(struct address_space *mapping,
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else
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else
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migrate_page_states(newpage, page);
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migrate_page_states(newpage, page);
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rc = MIGRATEPAGE_SUCCESS;
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unlock_buffers:
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bh = head;
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bh = head;
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do {
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do {
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unlock_buffer(bh);
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unlock_buffer(bh);
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@ -822,7 +809,7 @@ int buffer_migrate_page(struct address_space *mapping,
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} while (bh != head);
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} while (bh != head);
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return MIGRATEPAGE_SUCCESS;
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return rc;
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}
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}
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EXPORT_SYMBOL(buffer_migrate_page);
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EXPORT_SYMBOL(buffer_migrate_page);
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#endif
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#endif
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