Commit 4ac1c17b authored Jun 16, 2016 by Kirill A. Shutemov Committed by Richard Weinberger Jun 23, 2016

UBIFS: Implement ->migratepage()



During page migrations UBIFS might get confused
and the following assert triggers:
[  213.480000] UBIFS assert failed in ubifs_set_page_dirty at 1451 (pid 436)
[  213.490000] CPU: 0 PID: 436 Comm: drm-stress-test Not tainted 4.4.4-00176-geaa802524636-dirty #1008
[  213.490000] Hardware name: Allwinner sun4i/sun5i Families
[  213.490000] [<c0015e70>] (unwind_backtrace) from [<c0012cdc>] (show_stack+0x10/0x14)
[  213.490000] [<c0012cdc>] (show_stack) from [<c02ad834>] (dump_stack+0x8c/0xa0)
[  213.490000] [<c02ad834>] (dump_stack) from [<c0236ee8>] (ubifs_set_page_dirty+0x44/0x50)
[  213.490000] [<c0236ee8>] (ubifs_set_page_dirty) from [<c00fa0bc>] (try_to_unmap_one+0x10c/0x3a8)
[  213.490000] [<c00fa0bc>] (try_to_unmap_one) from [<c00fadb4>] (rmap_walk+0xb4/0x290)
[  213.490000] [<c00fadb4>] (rmap_walk) from [<c00fb1bc>] (try_to_unmap+0x64/0x80)
[  213.490000] [<c00fb1bc>] (try_to_unmap) from [<c010dc28>] (migrate_pages+0x328/0x7a0)
[  213.490000] [<c010dc28>] (migrate_pages) from [<c00d0cb0>] (alloc_contig_range+0x168/0x2f4)
[  213.490000] [<c00d0cb0>] (alloc_contig_range) from [<c010ec00>] (cma_alloc+0x170/0x2c0)
[  213.490000] [<c010ec00>] (cma_alloc) from [<c001a958>] (__alloc_from_contiguous+0x38/0xd8)
[  213.490000] [<c001a958>] (__alloc_from_contiguous) from [<c001ad44>] (__dma_alloc+0x23c/0x274)
[  213.490000] [<c001ad44>] (__dma_alloc) from [<c001ae08>] (arm_dma_alloc+0x54/0x5c)
[  213.490000] [<c001ae08>] (arm_dma_alloc) from [<c035cecc>] (drm_gem_cma_create+0xb8/0xf0)
[  213.490000] [<c035cecc>] (drm_gem_cma_create) from [<c035cf20>] (drm_gem_cma_create_with_handle+0x1c/0xe8)
[  213.490000] [<c035cf20>] (drm_gem_cma_create_with_handle) from [<c035d088>] (drm_gem_cma_dumb_create+0x3c/0x48)
[  213.490000] [<c035d088>] (drm_gem_cma_dumb_create) from [<c0341ed8>] (drm_ioctl+0x12c/0x444)
[  213.490000] [<c0341ed8>] (drm_ioctl) from [<c0121adc>] (do_vfs_ioctl+0x3f4/0x614)
[  213.490000] [<c0121adc>] (do_vfs_ioctl) from [<c0121d30>] (SyS_ioctl+0x34/0x5c)
[  213.490000] [<c0121d30>] (SyS_ioctl) from [<c000f2c0>] (ret_fast_syscall+0x0/0x34)

UBIFS is using PagePrivate() which can have different meanings across
filesystems. Therefore the generic page migration code cannot handle this
case correctly.
We have to implement our own migration function which basically does a
plain copy but also duplicates the page private flag.
UBIFS is not a block device filesystem and cannot use buffer_migrate_page().

Cc: stable@vger.kernel.org
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[rw: Massaged changelog, build fixes, etc...]
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Christoph Hellwig <hch@lst.de>

parent 1118dce7

fs/ubifs/file.c

+24 −0

Original line number	Diff line number	Diff line
		@@ -52,6 +52,7 @@
		#include "ubifs.h"
		#include <linux/mount.h>
		#include <linux/slab.h>
		#include <linux/migrate.h>

		static int read_block(struct inode inode, void addr, unsigned int block,
		struct ubifs_data_node *dn)
		@@ -1452,6 +1453,26 @@ static int ubifs_set_page_dirty(struct page *page)
		return ret;
		}

		#ifdef CONFIG_MIGRATION
		static int ubifs_migrate_page(struct address_space *mapping,
		struct page newpage, struct page page, enum migrate_mode mode)
		{
		int rc;

		rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
		if (rc != MIGRATEPAGE_SUCCESS)
		return rc;

		if (PagePrivate(page)) {
		ClearPagePrivate(page);
		SetPagePrivate(newpage);
		}

		migrate_page_copy(newpage, page);
		return MIGRATEPAGE_SUCCESS;
		}
		#endif

		static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
		{
		/*
		@@ -1591,6 +1612,9 @@ const struct address_space_operations ubifs_file_address_operations = {
		.write_end = ubifs_write_end,
		.invalidatepage = ubifs_invalidatepage,
		.set_page_dirty = ubifs_set_page_dirty,
		#ifdef CONFIG_MIGRATION
		.migratepage = ubifs_migrate_page,
		#endif
		.releasepage = ubifs_releasepage,
		};

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