On Tue, Oct 17, 2023 at 08:53:16PM +0200, Christoph Hellwig wrote:
> On Tue, Oct 17, 2023 at 08:53:21AM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@xxxxxxxxxx>
> >
> > Create get and set functions for rtbitmap words so that we can redefine
> > the ondisk format with a specific endianness. Note that this requires
> > the definition of a distinct type for ondisk rtbitmap words so that the
> > compiler can perform proper typechecking as we go back and forth.
> >
> > In the upcoming rtgroups feature, we're going to fix the problem that
> > rtwords are written in host endian order, which means we'll need the
> > distinct rtword/rtword_raw types.
>
> So per the last round I'd much prefer no exposing the xfs_rtword_raw
> to the callers. I've cooked up the patch below to do this, and it
> seems to survive the absolute basic testing so far. One interesting
> thing is that as far as I can tell all but one of the
> xfs_trans_log_buf calls in the pre-existing code were wrong as they
> were missing the usual '- 1' for the last parameter.
>
> For reasons I can't explain the version with this patch also happens
> to actually generate smaller binary code as well:
>
> hch@brick:~/work/xfs$ size xfs_rtbitmap.o*
> text data bss dec hex filename
> 7763 0 0 7763 1e53 xfs_rtbitmap.o.new
> 7833 0 0 7833 1e99 xfs_rtbitmap.o.old
Probably not having to maintain b and word as separate variables...
> ---
> diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
> index f8daaff947fce8..6ca48fe8a9e1d3 100644
> --- a/fs/xfs/libxfs/xfs_rtbitmap.c
> +++ b/fs/xfs/libxfs/xfs_rtbitmap.c
> @@ -90,20 +90,35 @@ xfs_rtbuf_get(
> /* Convert an ondisk bitmap word to its incore representation. */
> inline xfs_rtword_t
> xfs_rtbitmap_getword(
> - struct xfs_mount *mp,
> - union xfs_rtword_raw *wordptr)
> + struct xfs_buf *bp,
> + unsigned int index)
> {
> - return wordptr->old;
> + union xfs_rtword_raw *words = bp->b_addr;
> +
> + return words[index].old;
> }
>
> /* Set an ondisk bitmap word from an incore representation. */
> inline void
> xfs_rtbitmap_setword(
> - struct xfs_mount *mp,
> - union xfs_rtword_raw *wordptr,
> + struct xfs_buf *bp,
> + unsigned int index,
> xfs_rtword_t incore)
> {
> - wordptr->old = incore;
> + union xfs_rtword_raw *words = bp->b_addr;
> +
> + words[index].old = incore;
> +}
> +
> +static inline void
> +xfs_trans_log_rtbitmap(
> + struct xfs_trans *tp,
> + struct xfs_buf *bp,
> + int from,
> + int to)
> +{
> + xfs_trans_log_buf(tp, bp, from * sizeof(union xfs_rtword_raw),
> + to * sizeof(union xfs_rtword_raw) - 1);
> }
I'll make a separate patch with new xfs_trans_log_rt{bitmap,summary}
helpers. Dunno if we care about a Fixes: tag for that off by one error
since its only effect was to log more of the bitmap than was strictly
necessary and I don't think that's worth bothering the LTS folks about.
>
> /*
> @@ -118,7 +133,6 @@ xfs_rtfind_back(
> xfs_rtxnum_t limit, /* last rtext to look at */
> xfs_rtxnum_t *rtx) /* out: start rtext found */
> {
> - union xfs_rtword_raw *b; /* current word in buffer */
> int bit; /* bit number in the word */
> xfs_fileoff_t block; /* bitmap block number */
> struct xfs_buf *bp; /* buf for the block */
> @@ -145,14 +159,13 @@ xfs_rtfind_back(
> * Get the first word's index & point to it.
> */
> word = xfs_rtx_to_rbmword(mp, start);
> - b = xfs_rbmblock_wordptr(bp, word);
> bit = (int)(start & (XFS_NBWORD - 1));
> len = start - limit + 1;
> /*
> * Compute match value, based on the bit at start: if 1 (free)
> * then all-ones, else all-zeroes.
> */
> - incore = xfs_rtbitmap_getword(mp, b);
> + incore = xfs_rtbitmap_getword(bp, word);
> want = (incore & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
> /*
> * If the starting position is not word-aligned, deal with the
> @@ -195,12 +208,6 @@ xfs_rtfind_back(
> }
>
> word = mp->m_blockwsize - 1;
> - b = xfs_rbmblock_wordptr(bp, word);
> - } else {
> - /*
> - * Go on to the previous word in the buffer.
> - */
> - b--;
Yay this goes away!
> }
> } else {
> /*
<snip to a function that uses setword>
> @@ -566,12 +553,11 @@ xfs_rtmodify_range(
> xfs_rtxlen_t len, /* length of extent to modify */
> int val) /* 1 for free, 0 for allocated */
> {
> - union xfs_rtword_raw *b; /* current word in buffer */
> int bit; /* bit number in the word */
> xfs_fileoff_t block; /* bitmap block number */
> struct xfs_buf *bp; /* buf for the block */
> int error; /* error value */
> - union xfs_rtword_raw *first; /* first used word in the buffer */
> + int first; /* first used word in the buffer */
/me notes that the xfs_rtx_to_rbmword function returns an unsigned int,
will clean that up...
> int i; /* current bit number rel. to start */
> int lastbit; /* last useful bit in word */
> xfs_rtword_t mask; /* mask o frelevant bits for value */
> @@ -593,8 +579,7 @@ xfs_rtmodify_range(
> /*
> * Compute the starting word's address, and starting bit.
> */
> - word = xfs_rtx_to_rbmword(mp, start);
> - first = b = xfs_rbmblock_wordptr(bp, word);
> + first = word = xfs_rtx_to_rbmword(mp, start);
> bit = (int)(start & (XFS_NBWORD - 1));
> /*
> * 0 (allocated) => all zeroes; 1 (free) => all ones.
> @@ -613,12 +598,12 @@ xfs_rtmodify_range(
> /*
> * Set/clear the active bits.
> */
> - incore = xfs_rtbitmap_getword(mp, b);
> + incore = xfs_rtbitmap_getword(bp, word);
> if (val)
> incore |= mask;
> else
> incore &= ~mask;
> - xfs_rtbitmap_setword(mp, b, incore);
> + xfs_rtbitmap_setword(bp, word, incore);
Yay!
> i = lastbit - bit;
> /*
> * Go on to the next block if that's where the next word is
<snip more of the same>
> diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
> index 4e33e84afa7ad6..ec14e6adb8364a 100644
> --- a/fs/xfs/libxfs/xfs_rtbitmap.h
> +++ b/fs/xfs/libxfs/xfs_rtbitmap.h
> @@ -158,17 +158,6 @@ xfs_rbmblock_to_rtx(
> return rbmoff << mp->m_blkbit_log;
> }
>
> -/* Return a pointer to a bitmap word within a rt bitmap block. */
> -static inline union xfs_rtword_raw *
> -xfs_rbmblock_wordptr(
> - struct xfs_buf *bp,
> - unsigned int index)
> -{
> - union xfs_rtword_raw *words = bp->b_addr;
> -
> - return words + index;
> -}
Note that I still need this (and the _infoptr helper) for online repair
to be able to generate an in-memory replacement of the bitmap and
summary file and then be able to memcpy the words into the new ondisk
file.
That said, I also noticed that the _rtbitmap_[gs]etword and
_suminfo_{get,add} functions can be static inlines in xfs_rtbitmap.h, so
I'll put them right after here and the compiler will (hopefully)
collapse the nested inlines into something fairly compact.
Ok, I've made all those changes and I'll resend this patchset tomorrow
after letting it test overnight.
--D
> -
> /*
> * Convert a rt extent length and rt bitmap block number to a xfs_suminfo_t
> * offset within the rt summary file.
> @@ -285,10 +274,10 @@ xfs_filblks_t xfs_rtbitmap_blockcount(struct xfs_mount *mp, xfs_rtbxlen_t
> rtextents);
> unsigned long long xfs_rtbitmap_wordcount(struct xfs_mount *mp,
> xfs_rtbxlen_t rtextents);
> -xfs_rtword_t xfs_rtbitmap_getword(struct xfs_mount *mp,
> - union xfs_rtword_raw *wordptr);
> -void xfs_rtbitmap_setword(struct xfs_mount *mp,
> - union xfs_rtword_raw *wordptr, xfs_rtword_t incore);
> +xfs_rtword_t xfs_rtbitmap_getword(struct xfs_buf *bp, unsigned int index);
> +void xfs_rtbitmap_setword(struct xfs_buf *bp, unsigned int index,
> + xfs_rtword_t incore);
> +
> #else /* CONFIG_XFS_RT */
> # define xfs_rtfree_extent(t,b,l) (-ENOSYS)
> # define xfs_rtfree_blocks(t,rb,rl) (-ENOSYS)
>
