iomap: improve the warnings from iomap_swapfile_activate

Print the path name of the swapfile that failed to active to ease
debugging the problem and to avoid a scare if xfstests hits these
cases.  Also reword one warning a bit, as the error is not about
a file being on multiple devices, but one that has at least an
extent outside the main device known to the VFS and swap code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/fs/iomap/swapfile.c b/fs/iomap/swapfile.c
index a5e478de141744cd7fef9276b26e5dc0b55638f0..6250ca6a1f851d4be8d12f39e86f0d03508f6627 100644 (file)
--- a/fs/iomap/swapfile.c
+++ b/fs/iomap/swapfile.c
@@ -18,6 +18,7 @@ struct iomap_swapfile_info {
        uint64_t highest_ppage;         /* highest physical addr seen (pages) */
        unsigned long nr_pages;         /* number of pages collected */
        int nr_extents;                 /* extent count */
+       struct file *file;
 };
 
 /*
@@ -70,6 +71,18 @@ static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
        return 0;
 }
 
+static int iomap_swapfile_fail(struct iomap_swapfile_info *isi, const char *str)
+{
+       char *buf, *p = ERR_PTR(-ENOMEM);
+
+       buf = kmalloc(PATH_MAX, GFP_KERNEL);
+       if (buf)
+               p = file_path(isi->file, buf, PATH_MAX);
+       pr_err("swapon: file %s %s\n", IS_ERR(p) ? "<unknown>" : p, str);
+       kfree(buf);
+       return -EINVAL;
+}
+
 /*
  * Accumulate iomaps for this swap file.  We have to accumulate iomaps because
  * swap only cares about contiguous page-aligned physical extents and makes no
@@ -89,28 +102,20 @@ static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
                break;
        case IOMAP_INLINE:
                /* No inline data. */
-               pr_err("swapon: file is inline\n");
-               return -EINVAL;
+               return iomap_swapfile_fail(isi, "is inline");
        default:
-               pr_err("swapon: file has unallocated extents\n");
-               return -EINVAL;
+               return iomap_swapfile_fail(isi, "has unallocated extents");
        }
 
        /* No uncommitted metadata or shared blocks. */
-       if (iomap->flags & IOMAP_F_DIRTY) {
-               pr_err("swapon: file is not committed\n");
-               return -EINVAL;
-       }
-       if (iomap->flags & IOMAP_F_SHARED) {
-               pr_err("swapon: file has shared extents\n");
-               return -EINVAL;
-       }
+       if (iomap->flags & IOMAP_F_DIRTY)
+               return iomap_swapfile_fail(isi, "is not committed");
+       if (iomap->flags & IOMAP_F_SHARED)
+               return iomap_swapfile_fail(isi, "has shared extents");
 
        /* Only one bdev per swap file. */
-       if (iomap->bdev != isi->sis->bdev) {
-               pr_err("swapon: file is on multiple devices\n");
-               return -EINVAL;
-       }
+       if (iomap->bdev != isi->sis->bdev)
+               return iomap_swapfile_fail(isi, "outside the main device");
 
        if (isi->iomap.length == 0) {
                /* No accumulated extent, so just store it. */
@@ -139,6 +144,7 @@ int iomap_swapfile_activate(struct swap_info_struct *sis,
        struct iomap_swapfile_info isi = {
                .sis = sis,
                .lowest_ppage = (sector_t)-1ULL,
+               .file = swap_file,
        };
        struct address_space *mapping = swap_file->f_mapping;
        struct inode *inode = mapping->host;