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. > > 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
