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    Subject[PATCH 2/7] debugfs: add debugfs_create_int
    Date
    Introduce debugfs_create_int() for creating a debugfs file that is used to
    read and write an int value.

    It will be used by notifier error injection and there are two potential
    users of it (ceph/writeback_cngestion_kb and ocd/count on avr32)

    Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
    Cc: Greg Kroah-Hartman <gregkh@suse.de>
    ---
    fs/debugfs/file.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++
    include/linux/debugfs.h | 9 +++++++
    2 files changed, 65 insertions(+), 0 deletions(-)

    diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
    index 90f7657..05cb1c2 100644
    --- a/fs/debugfs/file.c
    +++ b/fs/debugfs/file.c
    @@ -213,6 +213,62 @@ struct dentry *debugfs_create_u32(const char *name, mode_t mode,
    }
    EXPORT_SYMBOL_GPL(debugfs_create_u32);

    +static int debugfs_int_set(void *data, u64 val)
    +{
    + *(int *)data = val;
    + return 0;
    +}
    +
    +static int debugfs_int_get(void *data, u64 *val)
    +{
    + *val = *(int *)data;
    + return 0;
    +}
    +
    +DEFINE_SIMPLE_ATTRIBUTE(fops_int, debugfs_int_get, debugfs_int_set, "%lld\n");
    +DEFINE_SIMPLE_ATTRIBUTE(fops_int_ro, debugfs_int_get, NULL, "%lld\n");
    +DEFINE_SIMPLE_ATTRIBUTE(fops_int_wo, NULL, debugfs_int_set, "%lld\n");
    +
    +/**
    + * debugfs_create_int - create a debugfs file that is used to read and write an int value
    + * @name: a pointer to a string containing the name of the file to create.
    + * @mode: the permission that the file should have
    + * @parent: a pointer to the parent dentry for this file. This should be a
    + * directory dentry if set. If this parameter is %NULL, then the
    + * file will be created in the root of the debugfs filesystem.
    + * @value: a pointer to the variable that the file should read to and write
    + * from.
    + *
    + * This function creates a file in debugfs with the given name that
    + * contains the value of the variable @value. If the @mode variable is so
    + * set, it can be read from, and written to.
    + *
    + * This function will return a pointer to a dentry if it succeeds. This
    + * pointer must be passed to the debugfs_remove() function when the file is
    + * to be removed (no automatic cleanup happens if your module is unloaded,
    + * you are responsible here.) If an error occurs, %NULL will be returned.
    + *
    + * If debugfs is not enabled in the kernel, the value -%ENODEV will be
    + * returned. It is not wise to check for this value, but rather, check for
    + * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
    + * code.
    + */
    +struct dentry *debugfs_create_int(const char *name, mode_t mode,
    + struct dentry *parent, int *value)
    +{
    + const struct file_operations *fops = &fops_int;
    +
    + /* if there are no write bits set, make read only */
    + if (!(mode & S_IWUGO))
    + fops = &fops_int_ro;
    + /* if there are no read bits set, make write only */
    + if (!(mode & S_IRUGO))
    + fops = &fops_u32_wo;
    +
    + return debugfs_create_file(name, mode, parent, value, fops);
    +}
    +EXPORT_SYMBOL_GPL(debugfs_create_int);
    +
    static int debugfs_u64_set(void *data, u64 val)
    {
    *(u64 *)data = val;
    diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
    index e7d9b20..6300792 100644
    --- a/include/linux/debugfs.h
    +++ b/include/linux/debugfs.h
    @@ -55,6 +55,8 @@ struct dentry *debugfs_create_u16(const char *name, mode_t mode,
    struct dentry *parent, u16 *value);
    struct dentry *debugfs_create_u32(const char *name, mode_t mode,
    struct dentry *parent, u32 *value);
    +struct dentry *debugfs_create_int(const char *name, mode_t mode,
    + struct dentry *parent, int *value);
    struct dentry *debugfs_create_u64(const char *name, mode_t mode,
    struct dentry *parent, u64 *value);
    struct dentry *debugfs_create_x8(const char *name, mode_t mode,
    @@ -139,6 +141,13 @@ static inline struct dentry *debugfs_create_u32(const char *name, mode_t mode,
    return ERR_PTR(-ENODEV);
    }

    +static inline struct dentry *debugfs_create_int(const char *name, mode_t mode,
    + struct dentry *parent,
    + int *value);
    +{
    + return ERR_PTR(-ENODEV);
    +}
    +
    static inline struct dentry *debugfs_create_u64(const char *name, mode_t mode,
    struct dentry *parent,
    u64 *value)
    --
    1.7.4.4


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