Commit 39a86958 authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

f2fs: refactor ->page_mkwrite() flow 



Thread A				Thread B
- f2fs_vm_page_mkwrite
					- f2fs_setattr
					 - down_write(i_mmap_sem)
					 - truncate_setsize
					 - f2fs_truncate
					 - up_write(i_mmap_sem)
 - f2fs_reserve_block
 reserve NEW_ADDR
 - skip dirty page due to truncation

1. we don't need to rserve new block address for a truncated page.
2. dn.data_blkaddr is used out of node page lock coverage.

Refactor ->page_mkwrite() flow to fix above issues:
- use __do_map_lock() to avoid racing checkpoint()
- lock data page in prior to dnode page
- cover f2fs_reserve_block with i_mmap_sem lock
- wait page writeback before zeroing page

Signed-off-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent bab475c5

fs/f2fs/data.c

+1 −1
Original line number Diff line number Diff line
@@ -972,7 +972,7 @@ map_blocks: 
	return err;

}



static inline void __do_map_lock(struct f2fs_sb_info *sbi, int flag, bool lock)

void __do_map_lock(struct f2fs_sb_info *sbi, int flag, bool lock)

{

	if (flag == F2FS_GET_BLOCK_PRE_AIO) {

		if (lock)

fs/f2fs/f2fs.h

+1 −0
Original line number Diff line number Diff line
@@ -3055,6 +3055,7 @@ struct page *f2fs_get_lock_data_page(struct inode *inode, pgoff_t index, 
struct page *f2fs_get_new_data_page(struct inode *inode,

			struct page *ipage, pgoff_t index, bool new_i_size);

int f2fs_do_write_data_page(struct f2fs_io_info *fio);

void __do_map_lock(struct f2fs_sb_info *sbi, int flag, bool lock);

int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,

			int create, int flag);

int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,

fs/f2fs/file.c

+22 −23
Original line number Diff line number Diff line
@@ -47,7 +47,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) 
	struct page *page = vmf->page;

	struct inode *inode = file_inode(vmf->vma->vm_file);

	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

	struct dnode_of_data dn;

	struct dnode_of_data dn = { .node_changed = false };

	int err;



	if (unlikely(f2fs_cp_error(sbi))) {
@@ -59,19 +59,6 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) 


	f2fs_bug_on(sbi, f2fs_has_inline_data(inode));



	/* block allocation */

	f2fs_lock_op(sbi);

	set_new_dnode(&dn, inode, NULL, NULL, 0);

	err = f2fs_reserve_block(&dn, page->index);

	if (err) {

		f2fs_unlock_op(sbi);

		goto out;

	}

	f2fs_put_dnode(&dn);

	f2fs_unlock_op(sbi);



	f2fs_balance_fs(sbi, dn.node_changed);



	file_update_time(vmf->vma->vm_file);

	down_read(&F2FS_I(inode)->i_mmap_sem);

	lock_page(page);
@@ -83,11 +70,28 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) 
		goto out_sem;

	}



	/* block allocation */

	__do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, true);

	set_new_dnode(&dn, inode, NULL, NULL, 0);

	err = f2fs_get_block(&dn, page->index);

	f2fs_put_dnode(&dn);

	__do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, false);

	if (err) {

		unlock_page(page);

		goto out_sem;

	}



	/* fill the page */

	f2fs_wait_on_page_writeback(page, DATA, false);



	/* wait for GCed page writeback via META_MAPPING */

	f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);



	/*

	 * check to see if the page is mapped already (no holes)

	 */

	if (PageMappedToDisk(page))

		goto mapped;

		goto out_sem;



	/* page is wholly or partially inside EOF */

	if (((loff_t)(page->index + 1) << PAGE_SHIFT) >
@@ -104,16 +108,11 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) 
	f2fs_update_iostat(sbi, APP_MAPPED_IO, F2FS_BLKSIZE);



	trace_f2fs_vm_page_mkwrite(page, DATA);

mapped:

	/* fill the page */

	f2fs_wait_on_page_writeback(page, DATA, false);



	/* wait for GCed page writeback via META_MAPPING */

	f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);



out_sem:

	up_read(&F2FS_I(inode)->i_mmap_sem);

out:



	f2fs_balance_fs(sbi, dn.node_changed);



	sb_end_pagefault(inode->i_sb);

	f2fs_update_time(sbi, REQ_TIME);

err:

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