libext2fs: revert "try to always use PUNCH_HOLE for unix_discard"

Revert bcca9876a3428c10417c660b78933e6e70e8a5f5, because
fallocate(PUNCH_HOLE) on block devices was changed to use zeroout
instead of discard shortly after block device fallocate was merged.
zeroout isn't necessarily a "drop storage" operation like discard is,
so we prefer to use that on block devices.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 16e2052cd6cf74ed653dc9eeb3c8020a1686f68d..74fc8a75df7170f5c1e19a3693e8f19a639cb861 100644 (file)
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -1081,38 +1081,6 @@ static errcode_t unix_set_option(io_channel channel, const char *option,
 #define BLKDISCARD             _IO(0x12,119)
 #endif
 
-/*
- * Try a PUNCH_HOLE to unmap blocks, then BLKDISCARD if that doesn't work.
- * We prefer PUNCH_HOLE because it invalidates the page cache, even on block
- * devices.
- */
-static int __unix_discard(int fd, int is_bdev, off_t offset, off_t len)
-{
-#ifdef BLKDISCARD
-       __u64 range[2];
-#endif
-       int ret = -1;
-
-#if defined(HAVE_FALLOCATE) && defined(FALLOC_FL_PUNCH_HOLE) && defined(FALLOC_FL_KEEP_SIZE)
-       ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
-                       offset, len);
-       if (ret == 0)
-               return 0;
-#endif
-#ifdef BLKDISCARD
-       if (is_bdev) {
-               range[0] = (__u64)offset;
-               range[1] = (__u64)len;
-
-               ret = ioctl(fd, BLKDISCARD, &range);
-               if (ret == 0)
-                       return 0;
-       }
-#endif
-       errno = EOPNOTSUPP;
-       return ret;
-}
-
 static errcode_t unix_discard(io_channel channel, unsigned long long block,
                              unsigned long long count)
 {
@@ -1123,10 +1091,31 @@ static errcode_t unix_discard(io_channel channel, unsigned long long block,
        data = (struct unix_private_data *) channel->private_data;
        EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
 
-       ret = __unix_discard(data->dev,
-                       (channel->flags & CHANNEL_FLAGS_BLOCK_DEVICE),
-                       (off_t)(block) * channel->block_size + data->offset,
-                       (off_t)(count) * channel->block_size);
+       if (channel->flags & CHANNEL_FLAGS_BLOCK_DEVICE) {
+#ifdef BLKDISCARD
+               __u64 range[2];
+
+               range[0] = (__u64)(block) * channel->block_size + data->offset;
+               range[1] = (__u64)(count) * channel->block_size;
+
+               ret = ioctl(data->dev, BLKDISCARD, &range);
+#else
+               goto unimplemented;
+#endif
+       } else {
+#if defined(HAVE_FALLOCATE) && defined(FALLOC_FL_PUNCH_HOLE)
+               /*
+                * If we are not on block device, try to use punch hole
+                * to reclaim free space.
+                */
+               ret = fallocate(data->dev,
+                               FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+                               (off_t)(block) * channel->block_size + data->offset,
+                               (off_t)(count) * channel->block_size);
+#else
+               goto unimplemented;
+#endif
+       }
        if (ret < 0) {
                if (errno == EOPNOTSUPP)
                        goto unimplemented;