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ext4: add support for reading sparse files

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Add support for sparse files in ext4. Also implement read-ahead, which
greatly increases the performance when transferring files from ext4.

Both features implemented by Damjan Jovanovic.

PR:		205816
MFC after:	1 week
This commit is contained in:
pfg 2016-01-11 19:14:55 +00:00
parent 8c83f31276
commit 52388dd9b7
4 changed files with 80 additions and 34 deletions
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29
sys/fs/ext2fs/ext2_bmap.c
View File

@ -102,9 +102,6 @@ ext4_bmapext(struct vnode *vp, int32_t bn, int64_t *bnp, int *runp, int *runb)
fs = ip->i_e2fs;
lbn = bn;
/*
* TODO: need to implement read ahead to improve the performance.
*/
if (runp != NULL)
*runp = 0;
@ -112,15 +109,25 @@ ext4_bmapext(struct vnode *vp, int32_t bn, int64_t *bnp, int *runp, int *runb)
*runb = 0;
ext4_ext_find_extent(fs, ip, lbn, &path);
ep = path.ep_ext;
if (ep == NULL)
ret = EIO;
else {
*bnp = fsbtodb(fs, lbn - ep->e_blk +
(ep->e_start_lo | (daddr_t)ep->e_start_hi << 32));
if (path.ep_is_sparse) {
*bnp = -1;
if (runp != NULL)
*runp = path.ep_sparse_ext.e_len -
(lbn - path.ep_sparse_ext.e_blk) - 1;
} else {
ep = path.ep_ext;
if (ep == NULL)
ret = EIO;
else {
*bnp = fsbtodb(fs, lbn - ep->e_blk +
(ep->e_start_lo | (daddr_t)ep->e_start_hi << 32));
if (*bnp == 0)
*bnp = -1;
if (*bnp == 0)
*bnp = -1;
if (runp != NULL)
*runp = ep->e_len - (lbn - ep->e_blk) - 1;
}
}
if (path.ep_bp != NULL) {

26
sys/fs/ext2fs/ext2_extents.c
View File

@ -66,13 +66,14 @@ static void
ext4_ext_binsearch(struct inode *ip, struct ext4_extent_path *path, daddr_t lbn)
{
struct ext4_extent_header *ehp = path->ep_header;
struct ext4_extent *l, *r, *m;
struct ext4_extent *first, *l, *r, *m;
if (ehp->eh_ecount == 0)
return;
l = (struct ext4_extent *)(char *)(ehp + 1);
r = (struct ext4_extent *)(char *)(ehp + 1) + ehp->eh_ecount - 1;
first = (struct ext4_extent *)(char *)(ehp + 1);
l = first;
r = first + ehp->eh_ecount - 1;
while (l <= r) {
m = l + (r - l) / 2;
if (lbn < m->e_blk)
@ -81,7 +82,25 @@ ext4_ext_binsearch(struct inode *ip, struct ext4_extent_path *path, daddr_t lbn)
l = m + 1;
}
if (l == first) {
path->ep_sparse_ext.e_blk = lbn;
path->ep_sparse_ext.e_len = first->e_blk - lbn;
path->ep_sparse_ext.e_start_hi = 0;
path->ep_sparse_ext.e_start_lo = 0;
path->ep_is_sparse = 1;
return;
}
path->ep_ext = l - 1;
if (path->ep_ext->e_blk + path->ep_ext->e_len <= lbn) {
path->ep_sparse_ext.e_blk = lbn;
if (l <= (first + ehp->eh_ecount - 1))
path->ep_sparse_ext.e_len = l->e_blk - lbn;
else // XXX: where does it end?
path->ep_sparse_ext.e_len = 1;
path->ep_sparse_ext.e_start_hi = 0;
path->ep_sparse_ext.e_start_lo = 0;
path->ep_is_sparse = 1;
}
}
/*
@ -169,6 +188,7 @@ ext4_ext_find_extent(struct m_ext2fs *fs, struct inode *ip,
path->ep_depth = i;
path->ep_ext = NULL;
path->ep_index = NULL;
path->ep_is_sparse = 0;
ext4_ext_binsearch(ip, path, lbn);
return (path);

6
sys/fs/ext2fs/ext2_extents.h
View File

@ -84,7 +84,11 @@ struct ext4_extent_cache {
struct ext4_extent_path {
uint16_t ep_depth;
struct buf *ep_bp;
struct ext4_extent *ep_ext;
int ep_is_sparse;
union {
struct ext4_extent ep_sparse_ext;
struct ext4_extent *ep_ext;
};
struct ext4_extent_index *ep_index;
struct ext4_extent_header *ep_header;
};

53
sys/fs/ext2fs/ext2_vnops.c
View File

@ -1787,6 +1787,7 @@ ext2_ioctl(struct vop_ioctl_args *ap)
static int
ext4_ext_read(struct vop_read_args *ap)
{
static unsigned char zeroes[EXT2_MAX_BLOCK_SIZE];
struct vnode *vp;
struct inode *ip;
struct uio *uio;
@ -1831,11 +1832,15 @@ ext4_ext_read(struct vop_read_args *ap)
switch (cache_type) {
case EXT4_EXT_CACHE_NO:
ext4_ext_find_extent(fs, ip, lbn, &path);
ep = path.ep_ext;
if (path.ep_is_sparse)
ep = &path.ep_sparse_ext;
else
ep = path.ep_ext;
if (ep == NULL)
return (EIO);
ext4_ext_put_cache(ip, ep, EXT4_EXT_CACHE_IN);
ext4_ext_put_cache(ip, ep,
path.ep_is_sparse ? EXT4_EXT_CACHE_GAP : EXT4_EXT_CACHE_IN);
newblk = lbn - ep->e_blk + (ep->e_start_lo |
(daddr_t)ep->e_start_hi << 32);
@ -1848,7 +1853,7 @@ ext4_ext_read(struct vop_read_args *ap)
case EXT4_EXT_CACHE_GAP:
/* block has not been allocated yet */
return (0);
break;
case EXT4_EXT_CACHE_IN:
newblk = lbn - nex.e_blk + (nex.e_start_lo |
@ -1859,24 +1864,34 @@ ext4_ext_read(struct vop_read_args *ap)
panic("%s: invalid cache type", __func__);
}
error = bread(ip->i_devvp, fsbtodb(fs, newblk), size, NOCRED, &bp);
if (error) {
brelse(bp);
return (error);
}
size -= bp->b_resid;
if (size < xfersize) {
if (size == 0) {
bqrelse(bp);
break;
if (cache_type == EXT4_EXT_CACHE_GAP ||
(cache_type == EXT4_EXT_CACHE_NO && path.ep_is_sparse)) {
if (xfersize > sizeof(zeroes))
xfersize = sizeof(zeroes);
error = uiomove(zeroes, xfersize, uio);
if (error)
return (error);
} else {
error = bread(ip->i_devvp, fsbtodb(fs, newblk), size,
NOCRED, &bp);
if (error) {
brelse(bp);
return (error);
}
xfersize = size;
size -= bp->b_resid;
if (size < xfersize) {
if (size == 0) {
bqrelse(bp);
break;
}
xfersize = size;
}
error = uiomove(bp->b_data + blkoffset, xfersize, uio);
bqrelse(bp);
if (error)
return (error);
}
error = uiomove(bp->b_data + blkoffset, (int)xfersize, uio);
bqrelse(bp);
if (error)
return (error);
}
return (0);