On 2023/6/14 7:39, Jaegeuk Kim wrote:
This reverts commit 27161f13e3c3 "f2fs: avoid race in between read xattr & write xattr".
That introduced a deadlock case:
Thread #1:
[122554.641906][ T92] f2fs_getxattr+0xd4/0x5fc -> waiting for f2fs_down_read(&F2FS_I(inode)->i_xattr_sem);
[122554.641927][ T92] __f2fs_get_acl+0x50/0x284 [122554.641948][ T92] f2fs_init_acl+0x84/0x54c [122554.641969][ T92] f2fs_init_inode_metadata+0x460/0x5f0 [122554.641990][ T92] f2fs_add_inline_entry+0x11c/0x350 -> Locked dir->inode_page by f2fs_get_node_page()
[122554.642009][ T92] f2fs_do_add_link+0x100/0x1e4 [122554.642025][ T92] f2fs_create+0xf4/0x22c [122554.642047][ T92] vfs_create+0x130/0x1f4
Thread #2:
[123996.386358][ T92] __get_node_page+0x8c/0x504 -> waiting for dir->inode_page lock
[123996.386383][ T92] read_all_xattrs+0x11c/0x1f4 [123996.386405][ T92] __f2fs_setxattr+0xcc/0x528 [123996.386424][ T92] f2fs_setxattr+0x158/0x1f4 -> f2fs_down_write(&F2FS_I(inode)->i_xattr_sem);
[123996.386443][ T92] __f2fs_set_acl+0x328/0x430 [123996.386618][ T92] f2fs_set_acl+0x38/0x50 [123996.386642][ T92] posix_acl_chmod+0xc8/0x1c8 [123996.386669][ T92] f2fs_setattr+0x5e0/0x6bc [123996.386689][ T92] notify_change+0x4d8/0x580 [123996.386717][ T92] chmod_common+0xd8/0x184 [123996.386748][ T92] do_fchmodat+0x60/0x124 [123996.386766][ T92] __arm64_sys_fchmodat+0x28/0x3c
Let's take a look at the original issue back.
Thread A: Thread B: -f2fs_getxattr -lookup_all_xattrs -xnid = F2FS_I(inode)->i_xattr_nid; -f2fs_setxattr -__f2fs_setxattr -write_all_xattrs -truncate_xattr_node ... ... -write_checkpoint ... ... -alloc_nid <- nid reuse -get_node_page -f2fs_bug_on <- nid != node_footer->nid
One concern below:
Thread A: Thread B: - f2fs_getxattr - lookup_all_xattrs - read_inline_xattr - f2fs_get_node_page(ino) - memcpy inline xattr - f2fs_put_page - f2fs_setxattr - __f2fs_setxattr - __f2fs_setxattr - write_all_xattrs - write xnode and inode ---> inline xattr may out of update here. - read_xattr_block - f2fs_get_node_page(xnid) - memcpy xnode xattr - f2fs_put_page
Do we need to keep xattr_{get,set} being atomical operation?
Thanks,
I think we don't need to truncate xattr pages eagerly which introduces lots of data races without big benefits.
Cc: stable@vger.kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org
fs/f2fs/f2fs.h | 1 - fs/f2fs/super.c | 1 - fs/f2fs/xattr.c | 31 ++++++++----------------------- 3 files changed, 8 insertions(+), 25 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 3f5b161dd743..7b9af2d51656 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -838,7 +838,6 @@ struct f2fs_inode_info { /* avoid racing between foreground op and gc */ struct f2fs_rwsem i_gc_rwsem[2];
- struct f2fs_rwsem i_xattr_sem; /* avoid racing between reading and changing EAs */
int i_extra_isize; /* size of extra space located in i_addr */ kprojid_t i_projid; /* id for project quota */ diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 1b2c788ed80d..c917fa771f0e 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -1418,7 +1418,6 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb) INIT_LIST_HEAD(&fi->gdirty_list); init_f2fs_rwsem(&fi->i_gc_rwsem[READ]); init_f2fs_rwsem(&fi->i_gc_rwsem[WRITE]);
- init_f2fs_rwsem(&fi->i_xattr_sem);
/* Will be used by directory only */ fi->i_dir_level = F2FS_SB(sb)->dir_level; diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c index 213805d3592c..bdc8a55085a2 100644 --- a/fs/f2fs/xattr.c +++ b/fs/f2fs/xattr.c @@ -433,7 +433,7 @@ static inline int write_all_xattrs(struct inode *inode, __u32 hsize, { struct f2fs_sb_info *sbi = F2FS_I_SB(inode); size_t inline_size = inline_xattr_size(inode);
- struct page *in_page = NULL;
- struct page *in_page = ipage; void *xattr_addr; void *inline_addr = NULL; struct page *xpage;
@@ -446,29 +446,19 @@ static inline int write_all_xattrs(struct inode *inode, __u32 hsize, /* write to inline xattr */ if (inline_size) {
if (ipage) {inline_addr = inline_xattr_addr(inode, ipage);} else {
if (!in_page) { in_page = f2fs_get_node_page(sbi, inode->i_ino); if (IS_ERR(in_page)) { f2fs_alloc_nid_failed(sbi, new_nid); return PTR_ERR(in_page); }
inline_addr = inline_xattr_addr(inode, in_page);
inline_addr = inline_xattr_addr(inode, in_page);
f2fs_wait_on_page_writeback(ipage ? ipage : in_page,NODE, true, true);/* no need to use xattr node block */
f2fs_wait_on_page_writeback(in_page, NODE, true, true);
err = f2fs_truncate_xattr_node(inode);f2fs_alloc_nid_failed(sbi, new_nid);if (err) {f2fs_put_page(in_page, 1);return err;} memcpy(inline_addr, txattr_addr, inline_size);set_page_dirty(ipage ? ipage : in_page);
set_page_dirty(in_page); goto in_page_out;@@ -502,12 +492,13 @@ static inline int write_all_xattrs(struct inode *inode, __u32 hsize, memcpy(xattr_addr, txattr_addr + inline_size, VALID_XATTR_BLOCK_SIZE); if (inline_size)
set_page_dirty(ipage ? ipage : in_page);
set_page_dirty(in_page);f2fs_put_page(xpage, 1); in_page_out:
- f2fs_put_page(in_page, 1);
- if (in_page != ipage)
f2fs_put_page(in_page, 1);@@ -528,10 +519,8 @@ int f2fs_getxattr(struct inode *inode, int index, const char *name, if (len > F2FS_NAME_LEN) return -ERANGE;
- f2fs_down_read(&F2FS_I(inode)->i_xattr_sem); error = lookup_all_xattrs(inode, ipage, index, len, name, &entry, &base_addr, &base_size, &is_inline);
- f2fs_up_read(&F2FS_I(inode)->i_xattr_sem); if (error) return error;
@@ -565,9 +554,7 @@ ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) int error; size_t rest = buffer_size;
- f2fs_down_read(&F2FS_I(inode)->i_xattr_sem); error = read_all_xattrs(inode, NULL, &base_addr);
- f2fs_up_read(&F2FS_I(inode)->i_xattr_sem); if (error) return error;
@@ -794,9 +781,7 @@ int f2fs_setxattr(struct inode *inode, int index, const char *name, f2fs_balance_fs(sbi, true); f2fs_lock_op(sbi);
- f2fs_down_write(&F2FS_I(inode)->i_xattr_sem); err = __f2fs_setxattr(inode, index, name, value, size, ipage, flags);
- f2fs_up_write(&F2FS_I(inode)->i_xattr_sem); f2fs_unlock_op(sbi);
f2fs_update_time(sbi, REQ_TIME);