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xfs: rewrite xfs_bmap_first_unused to make better use of xfs_iext_get_extent 

Look at the return value of xfs_iext_get_extent instead of figuring out
the extent count first and looping up to it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Christoph Hellwig 2017-10-19 11:08:52 -07:00 committed by Darrick J. Wong
parent 5936dc543c
commit 29b3e94a9c
1 changed files with 26 additions and 30 deletions
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56
fs/xfs/libxfs/xfs_bmap.c
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@ -1285,57 +1285,53 @@ error0:
}
/*
* Returns the file-relative block number of the first unused block(s)
* in the file with at least "len" logically contiguous blocks free.
* This is the lowest-address hole if the file has holes, else the first block
* past the end of file.
* Return 0 if the file is currently local (in-inode).
* Returns the relative block number of the first unused block(s) in the given
* fork with at least "len" logically contiguous blocks free. This is the
* lowest-address hole if the fork has holes, else the first block past the end
* of fork. Return 0 if the fork is currently local (in-inode).
*/
int /* error */
xfs_bmap_first_unused(
xfs_trans_t *tp, /* transaction pointer */
xfs_inode_t *ip, /* incore inode */
xfs_extlen_t len, /* size of hole to find */
xfs_fileoff_t *first_unused, /* unused block */
int whichfork) /* data or attr fork */
struct xfs_trans *tp, /* transaction pointer */
struct xfs_inode *ip, /* incore inode */
xfs_extlen_t len, /* size of hole to find */
xfs_fileoff_t *first_unused, /* unused block */
int whichfork) /* data or attr fork */
{
int error; /* error return value */
int idx; /* extent record index */
xfs_ifork_t *ifp; /* inode fork pointer */
xfs_fileoff_t lastaddr; /* last block number seen */
xfs_fileoff_t lowest; /* lowest useful block */
xfs_fileoff_t max; /* starting useful block */
xfs_extnum_t nextents; /* number of extent entries */
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
struct xfs_bmbt_irec got;
xfs_extnum_t idx = 0;
xfs_fileoff_t lastaddr = 0;
xfs_fileoff_t lowest, max;
int error;
ASSERT(XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_BTREE ||
XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_EXTENTS ||
XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL);
if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL) {
*first_unused = 0;
return 0;
}
ifp = XFS_IFORK_PTR(ip, whichfork);
if (!(ifp->if_flags & XFS_IFEXTENTS) &&
(error = xfs_iread_extents(tp, ip, whichfork)))
return error;
lowest = *first_unused;
nextents = xfs_iext_count(ifp);
for (idx = 0, lastaddr = 0, max = lowest; idx < nextents; idx++) {
struct xfs_bmbt_irec got;
xfs_iext_get_extent(ifp, idx, &got);
if (!(ifp->if_flags & XFS_IFEXTENTS)) {
error = xfs_iread_extents(tp, ip, whichfork);
if (error)
return error;
}
lowest = max = *first_unused;
while (xfs_iext_get_extent(ifp, idx++, &got)) {
/*
* See if the hole before this extent will work.
*/
if (got.br_startoff >= lowest + len &&
got.br_startoff - max >= len) {
*first_unused = max;
return 0;
}
got.br_startoff - max >= len)
break;
lastaddr = got.br_startoff + got.br_blockcount;
max = XFS_FILEOFF_MAX(lastaddr, lowest);
}
*first_unused = max;
return 0;
}