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    SubjectRe: [PATCH 19/24] Unionfs: Helper macros/inlines
    On Sun,  7 Jan 2007 23:13:11 -0500
    "Josef 'Jeff' Sipek" <jsipek@cs.sunysb.edu> wrote:

    > From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
    >
    > This patch contains many macros and inline functions used thoughout Unionfs.
    >
    > ..
    >
    > +#define ibstart(ino) (UNIONFS_I(ino)->bstart)
    > +#define ibend(ino) (UNIONFS_I(ino)->bend)
    > +
    > +/* Superblock to private data */
    > +#define UNIONFS_SB(super) ((struct unionfs_sb_info *)(super)->s_fs_info)
    > +#define sbstart(sb) 0
    > +#define sbend(sb) (UNIONFS_SB(sb)->bend)
    > +#define sbmax(sb) (UNIONFS_SB(sb)->bend + 1)
    > +
    > +/* File to private Data */
    > +#define UNIONFS_F(file) ((struct unionfs_file_info *)((file)->private_data))
    > +#define fbstart(file) (UNIONFS_F(file)->bstart)
    > +#define fbend(file) (UNIONFS_F(file)->bend)
    >
    > ...
    >
    > +#define dbstart(dent) (UNIONFS_D(dent)->bstart)
    > +#define set_dbstart(dent, val) do { UNIONFS_D(dent)->bstart = val; } while(0)
    > +#define dbend(dent) (UNIONFS_D(dent)->bend)
    > +#define set_dbend(dent, val) do { UNIONFS_D(dent)->bend = val; } while(0)
    > +#define dbopaque(dent) (UNIONFS_D(dent)->bopaque)
    > +#define set_dbopaque(dent, val) do { UNIONFS_D(dent)->bopaque = val; } while (0)

    Please prefer to use inlined C fucntions. Macros should only be used if
    there is some reason why an inlined fucntion will not work.

    > +#define lock_dentry(d) down(&UNIONFS_D(d)->sem)
    > +#define unlock_dentry(d) up(&UNIONFS_D(d)->sem)
    > +#define verify_locked(d)

    Ditto.

    Please use mutexes where possible. Semaphores should only be used when
    their counting feature is employed. And, arguably, in situations where a
    lock is locked and unlocked from different threads, because this presently
    triggers mutex debugging warnings, although we should find a way of fixing
    this in the mutex code.

    I can't say I like the name "lock_dentry" much. It sounds like a VFS
    function and we may well gain a generic lock_dentry() at some time in the
    future. unionfs_lock_dentry() would be a better choice.
    -
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