diff options
| -rw-r--r-- | fs/btrfs/disk-io.c | 4 | ||||
| -rw-r--r-- | fs/hugetlbfs/inode.c | 3 | ||||
| -rw-r--r-- | fs/nfs/internal.h | 2 | ||||
| -rw-r--r-- | fs/nfs/write.c | 4 | ||||
| -rw-r--r-- | include/linux/fs.h | 9 | ||||
| -rw-r--r-- | include/linux/migrate.h | 2 | ||||
| -rw-r--r-- | mm/migrate.c | 129 |
7 files changed, 106 insertions, 47 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index f99a099a7747..1375494c8cb6 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -872,7 +872,7 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, #ifdef CONFIG_MIGRATION static int btree_migratepage(struct address_space *mapping, - struct page *newpage, struct page *page) + struct page *newpage, struct page *page, bool sync) { /* * we can't safely write a btree page from here, @@ -887,7 +887,7 @@ static int btree_migratepage(struct address_space *mapping, if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) return -EAGAIN; - return migrate_page(mapping, newpage, page); + return migrate_page(mapping, newpage, page, sync); } #endif diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index e425ad9d0490..06fd4608a990 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -583,7 +583,8 @@ static int hugetlbfs_set_page_dirty(struct page *page) } static int hugetlbfs_migrate_page(struct address_space *mapping, - struct page *newpage, struct page *page) + struct page *newpage, struct page *page, + bool sync) { int rc; diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h index 5ee92538b063..114398a15830 100644 --- a/fs/nfs/internal.h +++ b/fs/nfs/internal.h @@ -332,7 +332,7 @@ void nfs_commit_release_pages(struct nfs_write_data *data); #ifdef CONFIG_MIGRATION extern int nfs_migrate_page(struct address_space *, - struct page *, struct page *); + struct page *, struct page *, bool); #else #define nfs_migrate_page NULL #endif diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 0c3885255f97..889e98bc5a21 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1688,7 +1688,7 @@ out_error: #ifdef CONFIG_MIGRATION int nfs_migrate_page(struct address_space *mapping, struct page *newpage, - struct page *page) + struct page *page, bool sync) { /* * If PagePrivate is set, then the page is currently associated with @@ -1703,7 +1703,7 @@ int nfs_migrate_page(struct address_space *mapping, struct page *newpage, nfs_fscache_release_page(page, GFP_KERNEL); - return migrate_page(mapping, newpage, page); + return migrate_page(mapping, newpage, page, sync); } #endif diff --git a/include/linux/fs.h b/include/linux/fs.h index a7409bc157e0..b92b73d0b2b9 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -609,9 +609,12 @@ struct address_space_operations { loff_t offset, unsigned long nr_segs); int (*get_xip_mem)(struct address_space *, pgoff_t, int, void **, unsigned long *); - /* migrate the contents of a page to the specified target */ + /* + * migrate the contents of a page to the specified target. If sync + * is false, it must not block. + */ int (*migratepage) (struct address_space *, - struct page *, struct page *); + struct page *, struct page *, bool); int (*launder_page) (struct page *); int (*is_partially_uptodate) (struct page *, read_descriptor_t *, unsigned long); @@ -2537,7 +2540,7 @@ extern int generic_check_addressable(unsigned, u64); #ifdef CONFIG_MIGRATION extern int buffer_migrate_page(struct address_space *, - struct page *, struct page *); + struct page *, struct page *, bool); #else #define buffer_migrate_page NULL #endif diff --git a/include/linux/migrate.h b/include/linux/migrate.h index e39aeecfe9a2..14e6d2a88475 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -11,7 +11,7 @@ typedef struct page *new_page_t(struct page *, unsigned long private, int **); extern void putback_lru_pages(struct list_head *l); extern int migrate_page(struct address_space *, - struct page *, struct page *); + struct page *, struct page *, bool); extern int migrate_pages(struct list_head *l, new_page_t x, unsigned long private, bool offlining, bool sync); diff --git a/mm/migrate.c b/mm/migrate.c index fc391985899f..4e86f3bacb85 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -216,6 +216,55 @@ out: pte_unmap_unlock(ptep, ptl); } +#ifdef CONFIG_BLOCK +/* Returns true if all buffers are successfully locked */ +static bool buffer_migrate_lock_buffers(struct buffer_head *head, bool sync) +{ + struct buffer_head *bh = head; + + /* Simple case, sync compaction */ + if (sync) { + do { + get_bh(bh); + lock_buffer(bh); + bh = bh->b_this_page; + + } while (bh != head); + + return true; + } + + /* async case, we cannot block on lock_buffer so use trylock_buffer */ + do { + get_bh(bh); + if (!trylock_buffer(bh)) { + /* + * We failed to lock the buffer and cannot stall in + * async migration. Release the taken locks + */ + struct buffer_head *failed_bh = bh; + put_bh(failed_bh); + bh = head; + while (bh != failed_bh) { + unlock_buffer(bh); + put_bh(bh); + bh = bh->b_this_page; + } + return false; + } + + bh = bh->b_this_page; + } while (bh != head); + return true; +} +#else +static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, + bool sync) +{ + return true; +} +#endif /* CONFIG_BLOCK */ + /* * Replace the page in the mapping. * @@ -225,7 +274,8 @@ out: * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. */ static int migrate_page_move_mapping(struct address_space *mapping, - struct page *newpage, struct page *page) + struct page *newpage, struct page *page, + struct buffer_head *head, bool sync) { int expected_count; void **pslot; @@ -255,6 +305,19 @@ static int migrate_page_move_mapping(struct address_space *mapping, } /* + * In the async migration case of moving a page with buffers, lock the + * buffers using trylock before the mapping is moved. If the mapping + * was moved, we later failed to lock the buffers and could not move + * the mapping back due to an elevated page count, we would have to + * block waiting on other references to be dropped. + */ + if (!sync && head && !buffer_migrate_lock_buffers(head, sync)) { + page_unfreeze_refs(page, expected_count); + spin_unlock_irq(&mapping->tree_lock); + return -EAGAIN; + } + + /* * Now we know that no one else is looking at the page. */ get_page(newpage); /* add cache reference */ @@ -409,13 +472,13 @@ EXPORT_SYMBOL(fail_migrate_page); * Pages are locked upon entry and exit. */ int migrate_page(struct address_space *mapping, - struct page *newpage, struct page *page) + struct page *newpage, struct page *page, bool sync) { int rc; BUG_ON(PageWriteback(page)); /* Writeback must be complete */ - rc = migrate_page_move_mapping(mapping, newpage, page); + rc = migrate_page_move_mapping(mapping, newpage, page, NULL, sync); if (rc) return rc; @@ -432,28 +495,28 @@ EXPORT_SYMBOL(migrate_page); * exist. */ int buffer_migrate_page(struct address_space *mapping, - struct page *newpage, struct page *page) + struct page *newpage, struct page *page, bool sync) { struct buffer_head *bh, *head; int rc; if (!page_has_buffers(page)) - return migrate_page(mapping, newpage, page); + return migrate_page(mapping, newpage, page, sync); head = page_buffers(page); - rc = migrate_page_move_mapping(mapping, newpage, page); + rc = migrate_page_move_mapping(mapping, newpage, page, head, sync); if (rc) return rc; - bh = head; - do { - get_bh(bh); - lock_buffer(bh); - bh = bh->b_this_page; - - } while (bh != head); + /* + * In the async case, migrate_page_move_mapping locked the buffers + * with an IRQ-safe spinlock held. In the sync case, the buffers + * need to be locked now + */ + if (sync) + BUG_ON(!buffer_migrate_lock_buffers(head, sync)); ClearPagePrivate(page); set_page_private(newpage, page_private(page)); @@ -530,10 +593,13 @@ static int writeout(struct address_space *mapping, struct page *page) * Default handling if a filesystem does not provide a migration function. */ static int fallback_migrate_page(struct address_space *mapping, - struct page *newpage, struct page *page) + struct page *newpage, struct page *page, bool sync) { - if (PageDirty(page)) + if (PageDirty(page)) { + if (!sync) + return -EBUSY; return writeout(mapping, page); + } /* * Buffers may be managed in a filesystem specific way. @@ -543,7 +609,7 @@ static int fallback_migrate_page(struct address_space *mapping, !try_to_release_page(page, GFP_KERNEL)) return -EAGAIN; - return migrate_page(mapping, newpage, page); + return migrate_page(mapping, newpage, page, sync); } /* @@ -579,29 +645,18 @@ static int move_to_new_page(struct page *newpage, struct page *page, mapping = page_mapping(page); if (!mapping) - rc = migrate_page(mapping, newpage, page); - else { + rc = migrate_page(mapping, newpage, page, sync); + else if (mapping->a_ops->migratepage) /* - * Do not writeback pages if !sync and migratepage is - * not pointing to migrate_page() which is nonblocking - * (swapcache/tmpfs uses migratepage = migrate_page). + * Most pages have a mapping and most filesystems provide a + * migratepage callback. Anonymous pages are part of swap + * space which also has its own migratepage callback. This + * is the most common path for page migration. */ - if (PageDirty(page) && !sync && - mapping->a_ops->migratepage != migrate_page) - rc = -EBUSY; - else if (mapping->a_ops->migratepage) - /* - * Most pages have a mapping and most filesystems - * should provide a migration function. Anonymous - * pages are part of swap space which also has its - * own migration function. This is the most common - * path for page migration. - */ - rc = mapping->a_ops->migratepage(mapping, - newpage, page); - else - rc = fallback_migrate_page(mapping, newpage, page); - } + rc = mapping->a_ops->migratepage(mapping, + newpage, page, sync); + else + rc = fallback_migrate_page(mapping, newpage, page, sync); if (rc) { newpage->mapping = NULL; |
