Messages in this thread Patch in this message | | | From | Chao Yu <> | Subject | [PATCH 3/4] f2fs: fix avoid race between truncate and background GC | Date | Fri, 27 Jul 2018 18:15:15 +0800 |
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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> --- fs/f2fs/data.c | 4 ++++ fs/f2fs/file.c | 33 +++++++++++++++++++-------------- 2 files changed, 23 insertions(+), 14 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 071224ded5f4..a29f3162b887 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -2214,10 +2214,14 @@ static void f2fs_write_failed(struct address_space *mapping, loff_t to) loff_t i_size = i_size_read(inode); if (to > i_size) { + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); down_write(&F2FS_I(inode)->i_mmap_sem); + truncate_pagecache(inode, i_size); f2fs_truncate_blocks(inode, i_size, true); + up_write(&F2FS_I(inode)->i_mmap_sem); + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); } } diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 7bd2412a8c37..ed5c9b0e0d0c 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -796,22 +796,25 @@ 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); + bool to_smaller = (attr->ia_size <= i_size_read(inode)); + + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); + down_write(&F2FS_I(inode)->i_mmap_sem); + + truncate_setsize(inode, attr->ia_size); + + if (to_smaller) 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); + /* + * do not trim all blocks after i_size if target size is + * larger than i_size. + */ + up_write(&F2FS_I(inode)->i_mmap_sem); + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); + if (err) + return err; + if (!to_smaller) { /* should convert inline inode here */ if (!f2fs_may_inline_data(inode)) { err = f2fs_convert_inline_inode(inode); @@ -958,6 +961,7 @@ 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_gc_rwsem[WRITE]); down_write(&F2FS_I(inode)->i_mmap_sem); truncate_inode_pages_range(mapping, blk_start, blk_end - 1); @@ -966,6 +970,7 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len) ret = f2fs_truncate_hole(inode, pg_start, pg_end); f2fs_unlock_op(sbi); up_write(&F2FS_I(inode)->i_mmap_sem); + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); } } -- 2.18.0.rc1
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