ext4: restart ext4_ext_remove_space() after transaction restart

If i_data_sem was internally dropped due to transaction restart, it is
necessary to restart path look-up because extents tree was possibly
modified by ext4_get_block().

https://bugzilla.kernel.org/show_bug.cgi?id=15827

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Acked-by: Jan Kara <jack@suse.cz>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ffcaa11..0a47bec 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -107,11 +107,8 @@ static int ext4_ext_truncate_extend_restart(handle_t *handle,
        if (err <= 0)
                return err;
        err = ext4_truncate_restart_trans(handle, inode, needed);
-       /*
-        * We have dropped i_data_sem so someone might have cached again
-        * an extent we are going to truncate.
-        */
-       ext4_ext_invalidate_cache(inode);
+       if (err == 0)
+               err = -EAGAIN;
 
        return err;
 }
@@ -2359,7 +2356,7 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
        int depth = ext_depth(inode);
        struct ext4_ext_path *path;
        handle_t *handle;
-       int i = 0, err = 0;
+       int i, err;
 
        ext_debug("truncate since %u\n", start);
 
@@ -2368,23 +2365,26 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
        if (IS_ERR(handle))
                return PTR_ERR(handle);
 
+again:
        ext4_ext_invalidate_cache(inode);
 
        /*
         * We start scanning from right side, freeing all the blocks
         * after i_size and walking into the tree depth-wise.
         */
+       depth = ext_depth(inode);
        path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_NOFS);
        if (path == NULL) {
                ext4_journal_stop(handle);
                return -ENOMEM;
        }
+       path[0].p_depth = depth;
        path[0].p_hdr = ext_inode_hdr(inode);
        if (ext4_ext_check(inode, path[0].p_hdr, depth)) {
                err = -EIO;
                goto out;
        }
-       path[0].p_depth = depth;
+       i = err = 0;
 
        while (i >= 0 && err == 0) {
                if (i == depth) {
@@ -2478,6 +2478,8 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
 out:
        ext4_ext_drop_refs(path);
        kfree(path);
+       if (err == -EAGAIN)
+               goto again;
        ext4_journal_stop(handle);
 
        return err;