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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: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu 2018-09-27 18:33:18 +08:00 committed by Jaegeuk Kim
parent bab475c541
commit 39a8695824
3 changed files with 24 additions and 24 deletions
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2
fs/f2fs/data.c
View File

@ -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)

1
fs/f2fs/f2fs.h
View File

@ -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,

45
fs/f2fs/file.c
View File

@ -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: