ext4: fix xattr deadlock

ext4_xattr_set_handle() eventually ends up calling
ext4_mark_inode_dirty() which tries to expand the inode by shifting
the EAs.  This leads to the xattr_sem being downed again and leading
to a deadlock.

This patch makes sure that if ext4_xattr_set_handle() is in the
call-chain, ext4_mark_inode_dirty() will not expand the inode.

Signed-off-by: Kalpak Shah <kalpak.shah@sun.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 8954208..362b0ed 100644 (file)
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -959,6 +959,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
        struct ext4_xattr_block_find bs = {
                .s = { .not_found = -ENODATA, },
        };
+       unsigned long no_expand;
        int error;
 
        if (!name)
@@ -966,6 +967,9 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
        if (strlen(name) > 255)
                return -ERANGE;
        down_write(&EXT4_I(inode)->xattr_sem);
+       no_expand = EXT4_I(inode)->i_state & EXT4_STATE_NO_EXPAND;
+       EXT4_I(inode)->i_state |= EXT4_STATE_NO_EXPAND;
+
        error = ext4_get_inode_loc(inode, &is.iloc);
        if (error)
                goto cleanup;
@@ -1042,6 +1046,8 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 cleanup:
        brelse(is.iloc.bh);
        brelse(bs.bh);
+       if (no_expand == 0)
+               EXT4_I(inode)->i_state &= ~EXT4_STATE_NO_EXPAND;
        up_write(&EXT4_I(inode)->xattr_sem);
        return error;
 }