[LogFS] Split large truncated into smaller chunks

[sfrench/cifs-2.6.git] / fs / logfs / readwrite.c

diff --git a/fs/logfs/readwrite.c b/fs/logfs/readwrite.c
index aca6c56a107ac488b389c7ef1a1ded326e788ea5..7e3a1e5fd76d6a77a2b164cfd28e4d93e0f81204 100644 (file)
--- a/fs/logfs/readwrite.c
+++ b/fs/logfs/readwrite.c
@@ -1837,19 +1837,37 @@ static int __logfs_truncate(struct inode *inode, u64 size)
        return logfs_truncate_direct(inode, size);
 }
 
-int logfs_truncate(struct inode *inode, u64 size)
+/*
+ * Truncate, by changing the segment file, can consume a fair amount
+ * of resources.  So back off from time to time and do some GC.
+ * 8 or 2048 blocks should be well within safety limits even if
+ * every single block resided in a different segment.
+ */
+#define TRUNCATE_STEP  (8 * 1024 * 1024)
+int logfs_truncate(struct inode *inode, u64 target)
 {
        struct super_block *sb = inode->i_sb;
-       int err;
+       u64 size = i_size_read(inode);
+       int err = 0;
 
-       logfs_get_wblocks(sb, NULL, 1);
-       err = __logfs_truncate(inode, size);
-       if (!err)
-               err = __logfs_write_inode(inode, 0);
-       logfs_put_wblocks(sb, NULL, 1);
+       size = ALIGN(size, TRUNCATE_STEP);
+       while (size > target) {
+               if (size > TRUNCATE_STEP)
+                       size -= TRUNCATE_STEP;
+               else
+                       size = 0;
+               if (size < target)
+                       size = target;
+
+               logfs_get_wblocks(sb, NULL, 1);
+               err = __logfs_truncate(inode, target);
+               if (!err)
+                       err = __logfs_write_inode(inode, 0);
+               logfs_put_wblocks(sb, NULL, 1);
+       }
 
        if (!err)
-               err = vmtruncate(inode, size);
+               err = vmtruncate(inode, target);
 
        /* I don't trust error recovery yet. */
        WARN_ON(err);