Hi Andreas,
I only have a few nitpicks...
On 10/04/18 18:39, Andreas Gruenbacher wrote:
Rewrite function hole_size so that it computes the entire size of a
hole. Previously, the hole size returned wasn't guaranteed to span the
entire hole and multiple invocations of hole_size could be needed to
reach the next bit of data.
Signed-off-by: Andreas Gruenbacher <[email protected]>
---
fs/gfs2/bmap.c | 106 ++++++++++++++++++++++++++++++++++++---------------------
1 file changed, 67 insertions(+), 39 deletions(-)
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 8c25a64d8ae0..14c21825b890 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -279,6 +279,12 @@ static inline __be64 *metapointer(unsigned int height,
const struct metapath *mp
return p + mp->mp_list[height];
}
+static inline const __be64 *metaend(unsigned int height, const struct metapath *mp)
+{
+ const struct buffer_head *bh = mp->mp_bh[height];
+ return (const __be64 *)(bh->b_data + bh->b_size);
+}
+
static void gfs2_metapath_ra(struct gfs2_glock *gl, __be64 *start, __be64
*end)
{
const __be64 *t;
@@ -631,56 +637,78 @@ static int gfs2_iomap_alloc(struct inode *inode, struct
iomap *iomap,
* hole_size - figure out the size of a hole
* @inode: The inode
* @lblock: The logical starting block number
- * @mp: The metapath
+ * @mp: The metapath at lblock
+ * @pholesz: The hole size in bytes (output)
+ *
+ * This function modifies @mp.
*
- * Returns: The hole size in bytes
+ * Returns: errno on error
*
*/
-static u64 hole_size(struct inode *inode, sector_t lblock, struct metapath *mp)
+static int hole_size(struct inode *inode, sector_t lblock, struct metapath *mp,
+ u64 *pholesz)
{
+ sector_t lblock_end = (i_size_read(inode) + i_blocksize(inode) - 1) >>
+ inode->i_blkbits;
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_sbd *sdp = GFS2_SB(inode);
- struct metapath mp_eof;
- u64 factor = 1;
- int hgt;
- u64 holesz = 0;
const __be64 *first, *end, *ptr;
- const struct buffer_head *bh;
- u64 lblock_stop = (i_size_read(inode) - 1) >> inode->i_blkbits;
- int zeroptrs;
- bool done = false;
-
- /* Get another metapath, to the very last byte */
- find_metapath(sdp, lblock_stop, &mp_eof, ip->i_height);
- for (hgt = ip->i_height - 1; hgt >= 0 && !done; hgt--) {
- bh = mp->mp_bh[hgt];
- if (bh) {
- zeroptrs = 0;
- first = metapointer(hgt, mp);
- end = (const __be64 *)(bh->b_data + bh->b_size);
-
- for (ptr = first; ptr < end; ptr++) {
- if (*ptr) {
- done = true;
- break;
- } else {
- zeroptrs++;
- }
+ u64 holesz = 0, factor = 1;
+ int hgt, ret;
hgt could be unsigned for consistency and checking.
+
+ for (hgt = ip->i_height - 1; hgt >= mp->mp_aheight; hgt--)
+ factor *= sdp->sd_inptrs;
+
+ for (;;) {
+ /* Count the number of zero pointers. */
+ first = metapointer(hgt, mp);
+ end = metaend(hgt, mp);
+ if (end - first > lblock_end - lblock - holesz)
+ end = first + lblock_end - lblock - holesz;
+ for (ptr = first; ptr < end; ptr++) {
+ if (*ptr) {
+ holesz += (ptr - first) * factor;
+ if (hgt == ip->i_height - 1)
+ goto out;
+ mp->mp_list[hgt] += (ptr - first);
+ goto fill_up_metapath;
}
- } else {
- zeroptrs = sdp->sd_inptrs;
}
- if (factor * zeroptrs >= lblock_stop - lblock + 1) {
- holesz = lblock_stop - lblock + 1;
- break;
+ holesz += (ptr - first) * factor;
+
+lower_metapath:
+ /* Decrease height of metapath. */
+ brelse(mp->mp_bh[hgt]);
+ mp->mp_bh[hgt] = NULL;
+ mp->mp_list[hgt] = 0;
+ if (!hgt)
+ goto out;
+ hgt--;
+ factor *= sdp->sd_inptrs;
+
+ /* Advance in metadata tree. */
+ (mp->mp_list[hgt])++;
+ first = metapointer(hgt, mp);
+ end = metaend(hgt, mp);
+ if (first >= end) {
+ if (!hgt)
+ goto out;
+ goto lower_metapath;
}
- holesz += factor * zeroptrs;
- factor *= sdp->sd_inptrs;
- if (hgt && (mp->mp_list[hgt - 1] < mp_eof.mp_list[hgt - 1]))
- (mp->mp_list[hgt - 1])++;
+fill_up_metapath:
+ /* Fill up metapath. */
Comment could be removed as the function name and the label are the same
as the comment :)
+ ret = fillup_metapath(ip, mp, ip->i_height - 1);
+ if (ret < 0)
+ return ret;
+ while (ret--) {
+ hgt++;
Could be taken out of the loop as hgt += ret
The flow is a little hard to follow but I don't see any obvious
problems. Has it been tested with directories as well as files?
Reviewed-by: Andrew Price <[email protected]>
Andy
+ factor /= sdp->sd_inptrs;
+ }
}
- return holesz << inode->i_blkbits;
+out:
+ *pholesz = holesz << inode->i_blkbits;
+ return 0;
}
static void gfs2_stuffed_iomap(struct inode *inode, struct iomap *iomap)
@@ -804,7 +832,7 @@ int gfs2_iomap_begin(struct inode *inode, loff_t pos,
loff_t length,
if (pos >= size)
ret = -ENOENT;
else if (height <= ip->i_height)
- iomap->length = hole_size(inode, lblock, &mp);
+ ret = hole_size(inode, lblock, &mp, &iomap->length);
else
iomap->length = size - pos;
}
