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f2fs: fix avoid race between truncate and background GC 

Thread A				Background GC
- f2fs_setattr isize to 0
 - truncate_setsize
					- gc_data_segment
					 - f2fs_get_read_data_page page #0
					  - set_page_dirty
					  - set_cold_data
 - f2fs_truncate

- f2fs_setattr isize to 4k
- read 4k <--- hit data in cached page #0

Above race condition can cause read out invalid data in a truncated
page, fix it by i_gc_rwsem[WRITE] lock.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu 2018-08-05 23:04:25 +08:00 committed by Jaegeuk Kim
parent c7079853c8
commit a33c150237
2 changed files with 28 additions and 15 deletions
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4
fs/f2fs/data.c
View File

@ -2199,8 +2199,12 @@ static void f2fs_write_failed(struct address_space *mapping, loff_t to)
if (to > i_size) {
down_write(&F2FS_I(inode)->i_mmap_sem);
down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
truncate_pagecache(inode, i_size);
f2fs_truncate_blocks(inode, i_size, true);
up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
up_write(&F2FS_I(inode)->i_mmap_sem);
}
}

39
fs/f2fs/file.c
View File

@ -796,22 +796,26 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
}
if (attr->ia_valid & ATTR_SIZE) {
if (attr->ia_size <= i_size_read(inode)) {
down_write(&F2FS_I(inode)->i_mmap_sem);
truncate_setsize(inode, attr->ia_size);
err = f2fs_truncate(inode);
up_write(&F2FS_I(inode)->i_mmap_sem);
if (err)
return err;
} else {
/*
* do not trim all blocks after i_size if target size is
* larger than i_size.
*/
down_write(&F2FS_I(inode)->i_mmap_sem);
truncate_setsize(inode, attr->ia_size);
up_write(&F2FS_I(inode)->i_mmap_sem);
bool to_smaller = (attr->ia_size <= i_size_read(inode));
down_write(&F2FS_I(inode)->i_mmap_sem);
down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
truncate_setsize(inode, attr->ia_size);
if (to_smaller)
err = f2fs_truncate(inode);
/*
* do not trim all blocks after i_size if target size is
* larger than i_size.
*/
up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
up_write(&F2FS_I(inode)->i_mmap_sem);
if (err)
return err;
if (!to_smaller) {
/* should convert inline inode here */
if (!f2fs_may_inline_data(inode)) {
err = f2fs_convert_inline_inode(inode);
@ -958,13 +962,18 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len)
blk_start = (loff_t)pg_start << PAGE_SHIFT;
blk_end = (loff_t)pg_end << PAGE_SHIFT;
down_write(&F2FS_I(inode)->i_mmap_sem);
down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
truncate_inode_pages_range(mapping, blk_start,
blk_end - 1);
f2fs_lock_op(sbi);
ret = f2fs_truncate_hole(inode, pg_start, pg_end);
f2fs_unlock_op(sbi);
up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
up_write(&F2FS_I(inode)->i_mmap_sem);
}
}