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Code Issues Releases Activity

- Set the next_alloc fields for an i-node after allocating a new block

Browse Source 
so that future allocations start with most recently allocated block
  rather than the beginning of the filesystem.
- Fix ext2_alloccg() to properly scan for 8 block chunks that are not
  aligned on 8-bit boundaries.  Previously this was causing new blocks
  to be allocated in a highly fragmented fashion (block 0 of a file at
  lbn N, block 1 at lbn N + 8, block 2 at lbn N + 16, etc.).
- Cosmetic tweaks to the currently-disabled fancy realloc sysctls.

PR:		kern/153584
Discussed with:	bde
Tested by:	Pedro F. Giffuni  giffunip at yahoo, Zheng Liu (lz)
This commit is contained in:
John Baldwin 2011-02-01 18:21:45 +00:00
parent f69c3436ee
commit c767faa558
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=218175
1 changed files with 59 additions and 15 deletions
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74
sys/fs/ext2fs/ext2_alloc.c
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@ -59,6 +59,10 @@ static u_long ext2_hashalloc(struct inode *, int, long, int,
int));
static daddr_t ext2_nodealloccg(struct inode *, int, daddr_t, int);
static daddr_t ext2_mapsearch(struct m_ext2fs *, char *, daddr_t);
#ifdef FANCY_REALLOC
static int ext2_reallocblks(struct vop_reallocblks_args *);
#endif
/*
* Allocate a block in the file system.
*
@ -108,13 +112,17 @@ ext2_alloc(ip, lbn, bpref, size, cred, bnp)
goto nospace;
if (bpref >= fs->e2fs->e2fs_bcount)
bpref = 0;
if (bpref == 0)
if (bpref == 0)
cg = ino_to_cg(fs, ip->i_number);
else
cg = dtog(fs, bpref);
bno = (daddr_t)ext2_hashalloc(ip, cg, bpref, fs->e2fs_bsize,
ext2_alloccg);
if (bno > 0) {
/* set next_alloc fields as done in block_getblk */
ip->i_next_alloc_block = lbn;
ip->i_next_alloc_goal = bno;
ip->i_blocks += btodb(fs->e2fs_bsize);
ip->i_flag |= IN_CHANGE | IN_UPDATE;
*bnp = bno;
@ -143,13 +151,14 @@ ext2_alloc(ip, lbn, bpref, size, cred, bnp)
*/
#ifdef FANCY_REALLOC
#include <sys/sysctl.h>
static int doasyncfree = 1;
static int doreallocblks = 1;
SYSCTL_NODE(_vfs, OID_AUTO, ext2fs, CTLFLAG_RW, 0, "EXT2FS filesystem");
#ifdef OPT_DEBUG
SYSCTL_INT(_debug, 14, doasyncfree, CTLFLAG_RW, &doasyncfree, 0, "");
#endif /* OPT_DEBUG */
static int doasyncfree = 1;
SYSCTL_INT(_vfs_ext2fs, OID_AUTO, doasyncfree, CTLFLAG_RW, &doasyncfree, 0,
"Use asychronous writes to update block pointers when freeing blocks");
static int doreallocblks = 1;
SYSCTL_INT(_vfs_ext2fs, OID_AUTO, doreallocblks, CTLFLAG_RW, &doreallocblks, 0, "");
#endif
int
@ -624,7 +633,8 @@ ext2_alloccg(struct inode *ip, int cg, daddr_t bpref, int size)
struct m_ext2fs *fs;
struct buf *bp;
struct ext2mount *ump;
int error, bno, start, end, loc;
daddr_t bno, runstart, runlen;
int bit, loc, end, error, start;
char *bbp;
/* XXX ondisk32 */
fs = ip->i_e2fs;
@ -665,17 +675,51 @@ ext2_alloccg(struct inode *ip, int cg, daddr_t bpref, int size)
else
start = 0;
end = howmany(fs->e2fs->e2fs_fpg, NBBY) - start;
retry:
runlen = 0;
runstart = 0;
for (loc = start; loc < end; loc++) {
if (bbp[loc] == 0) {
bno = loc * NBBY;
if (bbp[loc] == (char)0xff) {
runlen = 0;
continue;
}
/* Start of a run, find the number of high clear bits. */
if (runlen == 0) {
bit = fls(bbp[loc]);
runlen = NBBY - bit;
runstart = loc * NBBY + bit;
} else if (bbp[loc] == 0) {
/* Continue a run. */
runlen += NBBY;
} else {
/*
* Finish the current run. If it isn't long
* enough, start a new one.
*/
bit = ffs(bbp[loc]) - 1;
runlen += bit;
if (runlen >= 8) {
bno = runstart;
goto gotit;
}
/* Run was too short, start a new one. */
bit = fls(bbp[loc]);
runlen = NBBY - bit;
runstart = loc * NBBY + bit;
}
/* If the current run is long enough, use it. */
if (runlen >= 8) {
bno = runstart;
goto gotit;
}
}
for (loc = 0; loc < start; loc++) {
if (bbp[loc] == 0) {
bno = loc * NBBY;
goto gotit;
}
if (start != 0) {
end = start;
start = 0;
goto retry;
}
bno = ext2_mapsearch(fs, bbp, bpref);