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iversion: make inode_cmp_iversion{+raw} return bool instead of s64

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As Linus points out:

    The inode_cmp_iversion{+raw}() functions are pure and utter crap.

    Why?

    You say that they return 0/negative/positive, but they do so in a
    completely broken manner. They return that ternary value as the
    sequence number difference in a 's64', which means that if you
    actually care about that ternary value, and do the *sane* thing that
    the kernel-doc of the function implies is the right thing, you would
    do

        int cmp = inode_cmp_iversion(inode, old);
        if (cmp < 0 ...

    and as a result you get code that looks sane, but that doesn't
    actually *WORK* right.

Since none of the callers actually care about the ternary value here,
convert the inode_cmp_iversion{+raw} functions to just return a boolean
value (false for matching, true for non-matching).

This matches the existing use of these functions just fine, and makes it
simple to convert them to return a ternary value in the future if we
grow callers that need it.

With this change we can also reimplement inode_cmp_iversion in a simpler
way using inode_peek_iversion.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jeff Layton 2018-01-30 15:32:21 -05:00 committed by Linus Torvalds
parent 3da90b159b
commit c0cef30e4f
1 changed files with 8 additions and 12 deletions
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20
include/linux/iversion.h
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@ -309,13 +309,13 @@ inode_query_iversion(struct inode *inode)
* @inode: inode to check
* @old: old value to check against its i_version
*
* Compare the current raw i_version counter with a previous one. Returns 0 if
* they are the same or non-zero if they are different.
* Compare the current raw i_version counter with a previous one. Returns false
* if they are the same or true if they are different.
*/
static inline s64
static inline bool
inode_cmp_iversion_raw(const struct inode *inode, u64 old)
{
return (s64)inode_peek_iversion_raw(inode) - (s64)old;
return inode_peek_iversion_raw(inode) != old;
}
/**
@ -323,19 +323,15 @@ inode_cmp_iversion_raw(const struct inode *inode, u64 old)
* @inode: inode to check
* @old: old value to check against its i_version
*
* Compare an i_version counter with a previous one. Returns 0 if they are
* the same, a positive value if the one in the inode appears newer than @old,
* and a negative value if @old appears to be newer than the one in the
* inode.
* Compare an i_version counter with a previous one. Returns false if they are
* the same, and true if they are different.
*
* Note that we don't need to set the QUERIED flag in this case, as the value
* in the inode is not being recorded for later use.
*/
static inline s64
static inline bool
inode_cmp_iversion(const struct inode *inode, u64 old)
{
return (s64)(inode_peek_iversion_raw(inode) & ~I_VERSION_QUERIED) -
(s64)(old << I_VERSION_QUERIED_SHIFT);
return inode_peek_iversion(inode) != old;
}
#endif