f2fs: Avoid double lock for cp_rwsem during checkpoint

There could be a scenario where f2fs_sync_node_pages gets
called during checkpoint, which in turn tries to flush
inline data and calls iput(). This results in deadlock as
iput() tries to hold cp_rwsem, which is already held at the
beginning by checkpoint->block_operations().

Call stack :

Thread A		Thread B
f2fs_write_checkpoint()
- block_operations(sbi)
 - f2fs_lock_all(sbi);
  - down_write(&sbi->cp_rwsem);

                        - open()
                         - igrab()
                        - write() write inline data
                        - unlink()
- f2fs_sync_node_pages()
 - if (is_inline_node(page))
  - flush_inline_data()
   - ilookup()
     page = f2fs_pagecache_get_page()
     if (!page)
      goto iput_out;
     iput_out:
			-close()
			-iput()
       iput(inode);
       - f2fs_evict_inode()
        - f2fs_truncate_blocks()
         - f2fs_lock_op()
           - down_read(&sbi->cp_rwsem);

Fixes: 2049d4fcb057 ("f2fs: avoid multiple node page writes due to inline_data")
Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index d49f7a0..79e605f 100644 (file)
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1168,6 +1168,11 @@ static int block_operations(struct f2fs_sb_info *sbi)
        };
        int err = 0, cnt = 0;
 
+       /*
+        * Let's flush inline_data in dirty node pages.
+        */
+       f2fs_flush_inline_data(sbi);
+
 retry_flush_quotas:
        f2fs_lock_all(sbi);
        if (__need_flush_quota(sbi)) {

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 2a8ea81..7f3d259 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3282,6 +3282,7 @@ void f2fs_ra_node_page(struct f2fs_sb_info *sbi, nid_t nid);
 struct page *f2fs_get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid);
 struct page *f2fs_get_node_page_ra(struct page *parent, int start);
 int f2fs_move_node_page(struct page *node_page, int gc_type);
+int f2fs_flush_inline_data(struct f2fs_sb_info *sbi);
 int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
                        struct writeback_control *wbc, bool atomic,
                        unsigned int *seq_id);

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 1db8cab..e632de1 100644 (file)
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1807,6 +1807,53 @@ static bool flush_dirty_inode(struct page *page)
        return true;
 }
 
+int f2fs_flush_inline_data(struct f2fs_sb_info *sbi)
+{
+       pgoff_t index = 0;
+       struct pagevec pvec;
+       int nr_pages;
+       int ret = 0;
+
+       pagevec_init(&pvec);
+
+       while ((nr_pages = pagevec_lookup_tag(&pvec,
+                       NODE_MAPPING(sbi), &index, PAGECACHE_TAG_DIRTY))) {
+               int i;
+
+               for (i = 0; i < nr_pages; i++) {
+                       struct page *page = pvec.pages[i];
+
+                       if (!IS_DNODE(page))
+                               continue;
+
+                       lock_page(page);
+
+                       if (unlikely(page->mapping != NODE_MAPPING(sbi))) {
+continue_unlock:
+                               unlock_page(page);
+                               continue;
+                       }
+
+                       if (!PageDirty(page)) {
+                               /* someone wrote it for us */
+                               goto continue_unlock;
+                       }
+
+                       /* flush inline_data, if it's async context. */
+                       if (is_inline_node(page)) {
+                               clear_inline_node(page);
+                               unlock_page(page);
+                               flush_inline_data(sbi, ino_of_node(page));
+                               continue;
+                       }
+                       unlock_page(page);
+               }
+               pagevec_release(&pvec);
+               cond_resched();
+       }
+       return ret;
+}
+
 int f2fs_sync_node_pages(struct f2fs_sb_info *sbi,
                                struct writeback_control *wbc,
                                bool do_balance, enum iostat_type io_type)
@@ -1870,8 +1917,8 @@ continue_unlock:
                                goto continue_unlock;
                        }
 
-                       /* flush inline_data */
-                       if (is_inline_node(page)) {
+                       /* flush inline_data, if it's async context. */
+                       if (do_balance && is_inline_node(page)) {
                                clear_inline_node(page);
                                unlock_page(page);
                                flush_inline_data(sbi, ino_of_node(page));