Re: [f2fs-dev] [PATCH] f2fs: remove i_xattr_sem to avoid deadlock and fix the original issue

From: Chao Yu
Date: Tue Jun 27 2023 - 09:37:44 EST


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.



[ 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@xxxxxxxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
  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);


_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel