Famfs works on both /dev/pmem and /dev/dax devices. This commit introduces the function that opens a block (pmem) device and the struct dax_holder_operations that are needed for that ABI. In this commit, support for opening character /dev/dax is stubbed. A later commit introduces this capability. Signed-off-by: John Groves <john@xxxxxxxxxx> --- fs/famfs/famfs_inode.c | 83 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c index 3329aff000d1..82c861998093 100644 --- a/fs/famfs/famfs_inode.c +++ b/fs/famfs/famfs_inode.c @@ -68,5 +68,88 @@ static const struct super_operations famfs_ops = { .show_options = famfs_show_options, }; +/*************************************************************************************** + * dax_holder_operations for block dax + */ + +static int +famfs_blk_dax_notify_failure( + struct dax_device *dax_devp, + u64 offset, + u64 len, + int mf_flags) +{ + + pr_err("%s: dax_devp %llx offset %llx len %lld mf_flags %x\n", + __func__, (u64)dax_devp, (u64)offset, (u64)len, mf_flags); + return -EOPNOTSUPP; +} + +const struct dax_holder_operations famfs_blk_dax_holder_ops = { + .notify_failure = famfs_blk_dax_notify_failure, +}; + +static int +famfs_open_char_device( + struct super_block *sb, + struct fs_context *fc) +{ + pr_err("%s: Root device is %s, but your kernel does not support famfs on /dev/dax\n", + __func__, fc->source); + return -ENODEV; +} + +/** + * famfs_open_device() + * + * Open the memory device. If it looks like /dev/dax, call famfs_open_char_device(). + * Otherwise try to open it as a block/pmem device. + */ +static int +famfs_open_device( + struct super_block *sb, + struct fs_context *fc) +{ + struct famfs_fs_info *fsi = sb->s_fs_info; + struct dax_device *dax_devp; + u64 start_off = 0; + struct bdev_handle *handlep; + + if (fsi->dax_devp) { + pr_err("%s: already mounted\n", __func__); + return -EALREADY; + } + + if (strstr(fc->source, "/dev/dax")) /* There is probably a better way to check this */ + return famfs_open_char_device(sb, fc); + + if (!strstr(fc->source, "/dev/pmem")) { /* There is probably a better way to check this */ + pr_err("%s: primary backing dev (%s) is not pmem\n", + __func__, fc->source); + return -EINVAL; + } + + handlep = bdev_open_by_path(fc->source, FAMFS_BLKDEV_MODE, fsi, &fs_holder_ops); + if (IS_ERR(handlep->bdev)) { + pr_err("%s: failed blkdev_get_by_path(%s)\n", __func__, fc->source); + return PTR_ERR(handlep->bdev); + } + + dax_devp = fs_dax_get_by_bdev(handlep->bdev, &start_off, + fsi /* holder */, + &famfs_blk_dax_holder_ops); + if (IS_ERR(dax_devp)) { + pr_err("%s: unable to get daxdev from handlep->bdev\n", __func__); + bdev_release(handlep); + return -ENODEV; + } + fsi->bdev_handle = handlep; + fsi->dax_devp = dax_devp; + + pr_notice("%s: root device is block dax (%s)\n", __func__, fc->source); + return 0; +} + + MODULE_LICENSE("GPL"); -- 2.43.0