On 2018/7/29 14:13, Jaegeuk Kim wrote: > On 07/29, Chao Yu wrote: >> On 2018/7/29 9:58, Jaegeuk Kim wrote: >>> On 07/27, Chao Yu wrote: >>>> 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. >>> >>> We can truncate pages again after f2fs_truncate()? >> >> I think it can fix this issue, although it looks a little strange to truncate >> page cache twice. > > It'd be fine to do setsize first, and drop the cache later.
Let me rethink about this solution, since we have different case like punch_hole which may not need setsize. Thanks, > >> >> Thanks, >> >>> >>>> >>>> Signed-off-by: Chao Yu <[email protected]> >>>> --- >>>> 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 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
