On 24/02/26 12:56PM, Jonathan Cameron wrote: > 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. I tried to bulk apply those recommendations. > > > --- > > 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! Okay, undone. Everywhere. > > > + > > + 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. Changing to pr_debug. Would be good to have access to it in that way > > + 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. Done > > > > + return 0; > > +} > > + > > + > > > > MODULE_LICENSE("GPL"); Thanks, John >