btrfs-progs: check return of posix_fadvise

It seems highly unlikely that posix_fadvise could fail,
and even if it does, it was only advisory.  Still, if
it does, we could issue a notice to the user.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>

diff --git a/disk-io.c b/disk-io.c
index 897d0cf..97fbfbd 100644 (file)
--- a/disk-io.c
+++ b/disk-io.c
@@ -822,7 +822,8 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
                sb_bytenr = BTRFS_SUPER_INFO_OFFSET;
 
        /* try to drop all the caches */
-       posix_fadvise(fp, 0, 0, POSIX_FADV_DONTNEED);
+       if (posix_fadvise(fp, 0, 0, POSIX_FADV_DONTNEED))
+               fprintf(stderr, "Warning, could not drop caches\n");
 
        ret = btrfs_scan_one_device(fp, path, &fs_devices,
                                    &total_devs, sb_bytenr);
@@ -1282,7 +1283,8 @@ static int close_all_devices(struct btrfs_fs_info *fs_info)
                device = list_entry(next, struct btrfs_device, dev_list);
                if (device->fd) {
                        fsync(device->fd);
-                       posix_fadvise(device->fd, 0, 0, POSIX_FADV_DONTNEED);
+                       if (posix_fadvise(device->fd, 0, 0, POSIX_FADV_DONTNEED))
+                               fprintf(stderr, "Warning, could not drop caches\n");
                }
                close(device->fd);
        }

diff --git a/volumes.c b/volumes.c
index ca1b402..c0d02d1 100644 (file)
--- a/volumes.c
+++ b/volumes.c
@@ -193,7 +193,8 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, int flags)
                        goto fail;
                }
 
-               posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
+               if (posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED))
+                       fprintf(stderr, "Warning, could not drop caches\n");
 
                if (device->devid == fs_devices->latest_devid)
                        fs_devices->latest_bdev = fd;