From: Christoph Lameter Date: Wed, 1 Feb 2006 11:05:41 +0000 (-0800) Subject: [PATCH] Direct Migration V9: Avoid writeback / page_migrate() method X-Git-Tag: v2.6.16-rc2~99 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e965f9630c651fa4249039fd4b80c9392d07a856;p=linux-2.6 [PATCH] Direct Migration V9: Avoid writeback / page_migrate() method Migrate a page with buffers without requiring writeback This introduces a new address space operation migratepage() that may be used by a filesystem to implement its own version of page migration. A version is provided that migrates buffers attached to pages. Some filesystems (ext2, ext3, xfs) are modified to utilize this feature. The swapper address space operation are modified so that a regular migrate_page() will occur for anonymous pages without writeback (migrate_pages forces every anonymous page to have a swap entry). Signed-off-by: Mike Kravetz Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/buffer.c b/fs/buffer.c index 3dc712f29d..8bcbac87a2 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -3049,6 +3049,66 @@ asmlinkage long sys_bdflush(int func, long data) return 0; } +/* + * Migration function for pages with buffers. This function can only be used + * if the underlying filesystem guarantees that no other references to "page" + * exist. + */ +#ifdef CONFIG_MIGRATION +int buffer_migrate_page(struct page *newpage, struct page *page) +{ + struct address_space *mapping = page->mapping; + struct buffer_head *bh, *head; + + if (!mapping) + return -EAGAIN; + + if (!page_has_buffers(page)) + return migrate_page(newpage, page); + + head = page_buffers(page); + + if (migrate_page_remove_references(newpage, page, 3)) + return -EAGAIN; + + bh = head; + do { + get_bh(bh); + lock_buffer(bh); + bh = bh->b_this_page; + + } while (bh != head); + + ClearPagePrivate(page); + set_page_private(newpage, page_private(page)); + set_page_private(page, 0); + put_page(page); + get_page(newpage); + + bh = head; + do { + set_bh_page(bh, newpage, bh_offset(bh)); + bh = bh->b_this_page; + + } while (bh != head); + + SetPagePrivate(newpage); + + migrate_page_copy(newpage, page); + + bh = head; + do { + unlock_buffer(bh); + put_bh(bh); + bh = bh->b_this_page; + + } while (bh != head); + + return 0; +} +EXPORT_SYMBOL(buffer_migrate_page); +#endif + /* * Buffer-head allocation */ diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index e7d3f0522d..a717837f27 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -706,6 +706,7 @@ struct address_space_operations ext2_aops = { .bmap = ext2_bmap, .direct_IO = ext2_direct_IO, .writepages = ext2_writepages, + .migratepage = buffer_migrate_page, }; struct address_space_operations ext2_aops_xip = { @@ -723,6 +724,7 @@ struct address_space_operations ext2_nobh_aops = { .bmap = ext2_bmap, .direct_IO = ext2_direct_IO, .writepages = ext2_writepages, + .migratepage = buffer_migrate_page, }; /* diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c index 8824e84f8a..3fc4238e97 100644 --- a/fs/ext3/inode.c +++ b/fs/ext3/inode.c @@ -1559,6 +1559,7 @@ static struct address_space_operations ext3_ordered_aops = { .invalidatepage = ext3_invalidatepage, .releasepage = ext3_releasepage, .direct_IO = ext3_direct_IO, + .migratepage = buffer_migrate_page, }; static struct address_space_operations ext3_writeback_aops = { @@ -1572,6 +1573,7 @@ static struct address_space_operations ext3_writeback_aops = { .invalidatepage = ext3_invalidatepage, .releasepage = ext3_releasepage, .direct_IO = ext3_direct_IO, + .migratepage = buffer_migrate_page, }; static struct address_space_operations ext3_journalled_aops = { diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c index 1206267894..9892268e30 100644 --- a/fs/xfs/linux-2.6/xfs_aops.c +++ b/fs/xfs/linux-2.6/xfs_aops.c @@ -1462,4 +1462,5 @@ struct address_space_operations linvfs_aops = { .commit_write = generic_commit_write, .bmap = linvfs_bmap, .direct_IO = linvfs_direct_IO, + .migratepage = buffer_migrate_page, }; diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index a36a8e3b70..bfb4f2917b 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -1521,6 +1521,7 @@ xfs_mapping_buftarg( struct address_space *mapping; static struct address_space_operations mapping_aops = { .sync_page = block_sync_page, + .migratepage = fail_migrate_page, }; inode = new_inode(bdev->bd_inode->i_sb); diff --git a/include/linux/fs.h b/include/linux/fs.h index 84bb449b9b..e059da9470 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -363,6 +363,8 @@ struct address_space_operations { loff_t offset, unsigned long nr_segs); struct page* (*get_xip_page)(struct address_space *, sector_t, int); + /* migrate the contents of a page to the specified target */ + int (*migratepage) (struct page *, struct page *); }; struct backing_dev_info; @@ -1719,6 +1721,12 @@ extern void simple_release_fs(struct vfsmount **mount, int *count); extern ssize_t simple_read_from_buffer(void __user *, size_t, loff_t *, const void *, size_t); +#ifdef CONFIG_MIGRATION +extern int buffer_migrate_page(struct page *, struct page *); +#else +#define buffer_migrate_page NULL +#endif + extern int inode_change_ok(struct inode *, struct iattr *); extern int __must_check inode_setattr(struct inode *, struct iattr *); diff --git a/include/linux/swap.h b/include/linux/swap.h index 229b6d04b4..f3e17d5963 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -193,13 +193,18 @@ extern int isolate_lru_page(struct page *p); extern int putback_lru_pages(struct list_head *l); extern int migrate_page(struct page *, struct page *); extern void migrate_page_copy(struct page *, struct page *); +extern int migrate_page_remove_references(struct page *, struct page *, int); extern int migrate_pages(struct list_head *l, struct list_head *t, struct list_head *moved, struct list_head *failed); +extern int fail_migrate_page(struct page *, struct page *); #else static inline int isolate_lru_page(struct page *p) { return -ENOSYS; } static inline int putback_lru_pages(struct list_head *l) { return 0; } static inline int migrate_pages(struct list_head *l, struct list_head *t, struct list_head *moved, struct list_head *failed) { return -ENOSYS; } +/* Possible settings for the migrate_page() method in address_operations */ +#define migrate_page NULL +#define fail_migrate_page NULL #endif #ifdef CONFIG_MMU diff --git a/mm/rmap.c b/mm/rmap.c index f4b91d7aa5..df2c41c2a9 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -233,6 +233,7 @@ void remove_from_swap(struct page *page) delete_from_swap_cache(page); } +EXPORT_SYMBOL(remove_from_swap); #endif /* diff --git a/mm/swap_state.c b/mm/swap_state.c index 7b09ac503f..db8a3d3e16 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -27,6 +27,7 @@ static struct address_space_operations swap_aops = { .writepage = swap_writepage, .sync_page = block_sync_page, .set_page_dirty = __set_page_dirty_nobuffers, + .migratepage = migrate_page, }; static struct backing_dev_info swap_backing_dev_info = { diff --git a/mm/vmscan.c b/mm/vmscan.c index 5e98b86feb..5a610804cd 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -614,6 +614,15 @@ int putback_lru_pages(struct list_head *l) return count; } +/* + * Non migratable page + */ +int fail_migrate_page(struct page *newpage, struct page *page) +{ + return -EIO; +} +EXPORT_SYMBOL(fail_migrate_page); + /* * swapout a single page * page is locked upon entry, unlocked on exit @@ -659,6 +668,7 @@ unlock_retry: retry: return -EAGAIN; } +EXPORT_SYMBOL(swap_page); /* * Page migration was first developed in the context of the memory hotplug @@ -674,7 +684,7 @@ retry: * Remove references for a page and establish the new page with the correct * basic settings to be able to stop accesses to the page. */ -static int migrate_page_remove_references(struct page *newpage, +int migrate_page_remove_references(struct page *newpage, struct page *page, int nr_refs) { struct address_space *mapping = page_mapping(page); @@ -749,6 +759,7 @@ static int migrate_page_remove_references(struct page *newpage, return 0; } +EXPORT_SYMBOL(migrate_page_remove_references); /* * Copy the page to its new location @@ -788,6 +799,7 @@ void migrate_page_copy(struct page *newpage, struct page *page) if (PageWriteback(newpage)) end_page_writeback(newpage); } +EXPORT_SYMBOL(migrate_page_copy); /* * Common logic to directly migrate a single page suitable for @@ -815,6 +827,7 @@ int migrate_page(struct page *newpage, struct page *page) remove_from_swap(newpage); return 0; } +EXPORT_SYMBOL(migrate_page); /* * migrate_pages @@ -914,6 +927,11 @@ redo: if (!mapping) goto unlock_both; + if (mapping->a_ops->migratepage) { + rc = mapping->a_ops->migratepage(newpage, page); + goto unlock_both; + } + /* * Trigger writeout if page is dirty */