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f2fs: fix deadlock during inline_data conversion

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A deadlock can be occurred:
Thread 1]                             Thread 2]
 - f2fs_write_data_pages              - f2fs_write_begin
   - lock_page(page #0)
                                        - grab_cache_page(page #X)
                                        - get_node_page(inode_page)
                                        - grab_cache_page(page #0)
                                          : to convert inline_data
   - f2fs_write_data_page
     - f2fs_write_inline_data
       - get_node_page(inode_page)

In this case, trying to lock inode_page and page #0 causes deadlock.
In order to avoid this, this patch adds a rule for this locking policy,
which is that page #0 should be locked followed by inode_page lock.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Jaegeuk Kim 2014-11-25 10:59:45 -08:00
parent ce3e6d25f3
commit 5f72739583
1 changed files with 14 additions and 14 deletions
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28
fs/f2fs/data.c
View file

@ -936,6 +936,17 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
trace_f2fs_write_begin(inode, pos, len, flags);
f2fs_balance_fs(sbi);
/*
* We should check this at this moment to avoid deadlock on inode page
* and #0 page. The locking rule for inline_data conversion should be:
* lock_page(page #0) -> lock_page(inode_page)
*/
if (index != 0) {
err = f2fs_convert_inline_inode(inode);
if (err)
goto fail;
}
repeat:
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page) {
@ -960,21 +971,10 @@ repeat:
set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
sync_inode_page(&dn);
goto put_next;
} else if (page->index == 0) {
err = f2fs_convert_inline_page(&dn, page);
if (err)
goto put_fail;
} else {
struct page *p = grab_cache_page(inode->i_mapping, 0);
if (!p) {
err = -ENOMEM;
goto put_fail;
}
err = f2fs_convert_inline_page(&dn, p);
f2fs_put_page(p, 1);
if (err)
goto put_fail;
}
err = f2fs_convert_inline_page(&dn, page);
if (err)
goto put_fail;
}
err = f2fs_reserve_block(&dn, index);
if (err)