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    Subject[PATCH 4.9 045/105] device-dax: fix sysfs duplicate warnings
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Dan Williams <dan.j.williams@intel.com>

    commit bbb3be170ac2891526ad07b18af7db226879a8e7 upstream.

    Fix warnings of the form...

    WARNING: CPU: 10 PID: 4983 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80
    sysfs: cannot create duplicate filename '/class/dax/dax12.0'
    Call Trace:
    dump_stack+0x63/0x86
    __warn+0xcb/0xf0
    warn_slowpath_fmt+0x5a/0x80
    ? kernfs_path_from_node+0x4f/0x60
    sysfs_warn_dup+0x62/0x80
    sysfs_do_create_link_sd.isra.2+0x97/0xb0
    sysfs_create_link+0x25/0x40
    device_add+0x266/0x630
    devm_create_dax_dev+0x2cf/0x340 [dax]
    dax_pmem_probe+0x1f5/0x26e [dax_pmem]
    nvdimm_bus_probe+0x71/0x120

    ...by reusing the namespace id for the device-dax instance name.

    Now that we have decided that there will never by more than one
    device-dax instance per libnvdimm-namespace parent device [1], we can
    directly reuse the namepace ids. There are some possible follow-on
    cleanups, but those are saved for a later patch to simplify the -stable
    backport.

    [1]: https://lists.01.org/pipermail/linux-nvdimm/2016-December/008266.html

    Fixes: 98a29c39dc68 ("libnvdimm, namespace: allow creation of multiple pmem...")
    Cc: Jeff Moyer <jmoyer@redhat.com>
    Reported-by: Dariusz Dokupil <dariusz.dokupil@intel.com>
    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/dax/dax.c | 24 ++++++++++++++++--------
    drivers/dax/dax.h | 2 +-
    drivers/dax/pmem.c | 12 +++++++-----
    3 files changed, 24 insertions(+), 14 deletions(-)

    --- a/drivers/dax/dax.c
    +++ b/drivers/dax/dax.c
    @@ -546,7 +546,8 @@ static void dax_dev_release(struct devic
    struct dax_dev *dax_dev = to_dax_dev(dev);
    struct dax_region *dax_region = dax_dev->region;

    - ida_simple_remove(&dax_region->ida, dax_dev->id);
    + if (dax_dev->id >= 0)
    + ida_simple_remove(&dax_region->ida, dax_dev->id);
    ida_simple_remove(&dax_minor_ida, MINOR(dev->devt));
    dax_region_put(dax_region);
    iput(dax_dev->inode);
    @@ -581,7 +582,7 @@ static void unregister_dax_dev(void *dev
    }

    struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
    - struct resource *res, int count)
    + int id, struct resource *res, int count)
    {
    struct device *parent = dax_region->dev;
    struct dax_dev *dax_dev;
    @@ -608,10 +609,16 @@ struct dax_dev *devm_create_dax_dev(stru
    if (i < count)
    goto err_id;

    - dax_dev->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
    - if (dax_dev->id < 0) {
    - rc = dax_dev->id;
    - goto err_id;
    + if (id < 0) {
    + id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
    + dax_dev->id = id;
    + if (id < 0) {
    + rc = id;
    + goto err_id;
    + }
    + } else {
    + /* region provider owns @id lifetime */
    + dax_dev->id = -1;
    }

    minor = ida_simple_get(&dax_minor_ida, 0, 0, GFP_KERNEL);
    @@ -650,7 +657,7 @@ struct dax_dev *devm_create_dax_dev(stru
    dev->parent = parent;
    dev->groups = dax_attribute_groups;
    dev->release = dax_dev_release;
    - dev_set_name(dev, "dax%d.%d", dax_region->id, dax_dev->id);
    + dev_set_name(dev, "dax%d.%d", dax_region->id, id);
    rc = device_add(dev);
    if (rc) {
    kill_dax_dev(dax_dev);
    @@ -669,7 +676,8 @@ struct dax_dev *devm_create_dax_dev(stru
    err_inode:
    ida_simple_remove(&dax_minor_ida, minor);
    err_minor:
    - ida_simple_remove(&dax_region->ida, dax_dev->id);
    + if (dax_dev->id >= 0)
    + ida_simple_remove(&dax_region->ida, dax_dev->id);
    err_id:
    kfree(dax_dev);

    --- a/drivers/dax/dax.h
    +++ b/drivers/dax/dax.h
    @@ -21,5 +21,5 @@ struct dax_region *alloc_dax_region(stru
    int region_id, struct resource *res, unsigned int align,
    void *addr, unsigned long flags);
    struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
    - struct resource *res, int count);
    + int id, struct resource *res, int count);
    #endif /* __DAX_H__ */
    --- a/drivers/dax/pmem.c
    +++ b/drivers/dax/pmem.c
    @@ -58,13 +58,12 @@ static void dax_pmem_percpu_kill(void *d

    static int dax_pmem_probe(struct device *dev)
    {
    - int rc;
    void *addr;
    struct resource res;
    struct dax_dev *dax_dev;
    + int rc, id, region_id;
    struct nd_pfn_sb *pfn_sb;
    struct dax_pmem *dax_pmem;
    - struct nd_region *nd_region;
    struct nd_namespace_io *nsio;
    struct dax_region *dax_region;
    struct nd_namespace_common *ndns;
    @@ -122,14 +121,17 @@ static int dax_pmem_probe(struct device
    /* adjust the dax_region resource to the start of data */
    res.start += le64_to_cpu(pfn_sb->dataoff);

    - nd_region = to_nd_region(dev->parent);
    - dax_region = alloc_dax_region(dev, nd_region->id, &res,
    + rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", &region_id, &id);
    + if (rc != 2)
    + return -EINVAL;
    +
    + dax_region = alloc_dax_region(dev, region_id, &res,
    le32_to_cpu(pfn_sb->align), addr, PFN_DEV|PFN_MAP);
    if (!dax_region)
    return -ENOMEM;

    /* TODO: support for subdividing a dax region... */
    - dax_dev = devm_create_dax_dev(dax_region, &res, 1);
    + dax_dev = devm_create_dax_dev(dax_region, id, &res, 1);

    /* child dax_dev instances now own the lifetime of the dax_region */
    dax_region_put(dax_region);

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