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Date:   Wed, 28 Jun 2023 01:07:14 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <chao@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, stable@vger.kernel.org
Subject: Re: [f2fs-dev] [PATCH] f2fs: remove i_xattr_sem to avoid deadlock
 and fix the original issue
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References: <20230613233940.3643362-1-jaegeuk@kernel.org>
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 <8a370c8e-3b5f-5ea7-5839-76896d1ec69e@kernel.org>
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On 06/27, Chao Yu wrote:
> On 2023/6/26 21:11, Jaegeuk Kim wrote:
> > On 06/25, Chao Yu wrote:
> > > On 2023/6/25 15:26, Chao Yu wrote:
> > > > 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?
> > > 
> > > It seems xfstest starts to complain w/ below message...
> > 
> > I don't see any failure. Which test do you see?
> 
> 051, 083, ... 467, 642
> 
> Testcase doesn't fail, but kernel log shows inode has corrupted xattr.

I got it. It seems I had to fix the above issue only while keeping the sem. :(

> 
> > 
> > > 
> > > [ 3400.856443] F2FS-fs (vdc): inode (2187) has invalid last xattr entry, entry_size: 21468
> > > [ 3400.864042] F2FS-fs (vdc): inode (1595) has invalid last xattr entry, entry_size: 26580
> > > [ 3400.865764] F2FS-fs (vdc): inode (2187) has invalid last xattr entry, entry_size: 21468
> > > [ 3400.880067] F2FS-fs (vdc): inode (9839) has corrupted xattr
> > > [ 3400.880714] F2FS-fs (vdc): inode (10855) has corrupted xattr
> > > 
> > > Thanks,
> > > 
> > > > 
> > > > 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);
> > > > >  ????????? if (hsize <= inline_size) {
> > > > > -??????????? 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);
> > > > >  ????? set_page_dirty(xpage);
> > > > >  ????? f2fs_put_page(xpage, 1);
> > > > >  ? in_page_out:
> > > > > -??? f2fs_put_page(in_page, 1);
> > > > > +??? if (in_page != ipage)
> > > > > +??????? f2fs_put_page(in_page, 1);
> > > > >  ????? return err;
> > > > >  ? }
> > > > > @@ -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);
> > > > 
> > > > 
> > > > _______________________________________________
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