On Jun 15, 2018, at 2:56 PM, Luis R. Rodriguez <mcgrof@xxxxxxxxxx> wrote: > > Using raw zoned disks by filesystems requires special handling, only > f2fs currently supports this. All other filesystems do not support > dealing with zoned disks directly. > > As such using raw zoned disks is not supported by e2fsprogs, to use them you > need to use dm-zoned-tools, format them with dzadm, set the scheduler to > deadline, and then setup a dmsetup with zoned type, and somehow set > this up on every boot to live a semi-happy life for now. > > Even if you use dmsetup on every boot, the zoned disk is still exposed, > and a user may still think they have to run mkfs.ext[234] on it instead > of the /dev/mapper/ disk, and then mount it by mistake. > > In either case you may seem to believe your disk works and only eventually > end up with alignmet issues and perhaps lose you data. For instance the > below was observed with XFS but its expected ext[234] users would see > the same: If you are interested in ext4 and SMR drives, there were some patches developed to allow ext4 to work on zoned disks, essentially converting it to be a "lazy-journal log-structured" filesystem. That makes almost all of the filesystem IO linear (though we could avoid duplicate journal writes by writing large IOs directly to disk). This was presented at FAST'17 as "ext4-lazy", though I'm unable to find the patch that implemented this feature (it is not landed in the kernel yet). Maybe Ted could send out a URL for the patch, even if it is a WIP? Cheers, Andreas > [10869.959501] device-mapper: zoned reclaim: (sda): Align zone 865 wp 28349 to 30842 (wp+2493) blocks failed -5 > [10870.014488] sd 0:0:0:0: [sda] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE > [10870.016137] sd 0:0:0:0: [sda] tag#0 Sense Key : Illegal Request [current] > [10870.017696] sd 0:0:0:0: [sda] tag#0 Add. Sense: Unaligned write command > > We have to prevent these mistakes by avoiding mkfs use on zoned disks. > > Note that this not enough yet, if users are on old AHCI controllers, > the disks may not be detected as zoned. More work through udev may be > required to detect this situation old old parent PCI IDs for zoned > disks, and then prevent their use somehow. > > If you are stuck on using ext[234] there a udev rule out there [0], this is > far from perfect, and not fully what we want done upstream on Linux > distributions long term but it should at least help developers for now > enjoy their shiny big fat zoned disks with ext[234]. > > This check should help avoid having folks shoot themselves in the foot > for now with zoned disks. If you make the mistake to use mkfs.ext4 > on a zoned disk, you will now get: > > # mkfs.ext4 /dev/sda > mke2fs 1.44.2 (14-May-2018) > /dev/sda: zoned disk detected, refer to dm-zoned-tools for how to use while setting up superblock > > [0] https://lkml.kernel.org/r/20180614001147.1545-1-mcgrof@xxxxxxxxxx > > Cc: Damien Le Moal <damien.lemoal@xxxxxxx> > Cc: Bart Van Assche <Bart.VanAssche@xxxxxxx> > Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx> > --- > lib/ext2fs/ext2_err.et.in | 3 +++ > lib/ext2fs/initialize.c | 30 ++++++++++++++++++++++++++++++ > 2 files changed, 33 insertions(+) > > diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in > index 16abd23d..34ee5793 100644 > --- a/lib/ext2fs/ext2_err.et.in > +++ b/lib/ext2fs/ext2_err.et.in > @@ -545,4 +545,7 @@ ec EXT2_ET_INODE_CORRUPTED, > ec EXT2_ET_EA_INODE_CORRUPTED, > "Inode containing extended attribute value is corrupted" > > +ec EXT2_ET_ZONE_UNSUPPORTED, > + "zoned disk detected, refer to dm-zoned-tools for how to use" > + > end > diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c > index dbe798b2..cef8ebb2 100644 > --- a/lib/ext2fs/initialize.c > +++ b/lib/ext2fs/initialize.c > @@ -32,6 +32,10 @@ > #define O_BINARY 0 > #endif > > +#ifndef PATH_MAX > +#define PATH_MAX 1024 > +#endif > + > #if defined(__linux__) && defined(EXT2_OS_LINUX) > #define CREATOR_OS EXT2_OS_LINUX > #else > @@ -85,6 +89,28 @@ static unsigned int calc_reserved_gdt_blocks(ext2_filsys fs) > return rsv_gdb; > } > > +static errcode_t is_zoned_disk(const char *path) > +{ > + char str[PATH_MAX]; > + char *devname = basename(path); > + FILE *file; > + int len; > + > + len = snprintf(str, sizeof(str), "/sys/block/%s/queue/zoned", devname); > + > + /* Indicates truncation */ > + if (len >= PATH_MAX) > + return EXT2_ET_INVALID_ARGUMENT; > + > + file = fopen(str, "r"); > + if (!file) > + return 0; > + > + fclose(file); > + > + return EXT2_ET_ZONE_UNSUPPORTED; > +} > + > errcode_t ext2fs_initialize(const char *name, int flags, > struct ext2_super_block *param, > io_manager manager, ext2_filsys *ret_fs) > @@ -112,6 +138,10 @@ errcode_t ext2fs_initialize(const char *name, int flags, > if (!param || !ext2fs_blocks_count(param)) > return EXT2_ET_INVALID_ARGUMENT; > > + retval = is_zoned_disk(name); > + if (retval != 0) > + return retval; > + > retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs); > if (retval) > return retval; > -- > 2.17.1 > Cheers, Andreas
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