On Fri, 23 Feb 2024 11:41:54 -0600 John Groves <John@xxxxxxxxxx> wrote: > 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> Formatting comments mostly same as previous patches, so I'll stop repeating them. > --- > 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; Definitely don't force alignment in local parameter definitions. Always goes wrong and makes for unreadable mess in patches! > + > + if (fsi->dax_devp) { > + pr_err("%s: already mounted\n", __func__); Fine to fail but worth a error message? Not sure on convention on this but seems noisy and maybe in userspace control which isn't good. > + 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); pr_debug() Kernel log is too noisy anyway! + I'd assume we can tell this succeeded in lots of other ways. > + return 0; > +} > + > + > > MODULE_LICENSE("GPL");