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Cleanup redundant logic and add some comments to help explain how

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it works in lieu of potentially less clear code.

Sponsored by:	EMC / Isilon Storage Division
Discussed with:	Russell Cattelan
This commit is contained in:
bdrewery 2014-03-14 02:10:30 +00:00
parent f6fb7805fc
commit 3287a8bdc3
1 changed files with 17 additions and 14 deletions
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25
sys/fs/tmpfs/tmpfs_subr.c
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@ -348,6 +348,9 @@ tmpfs_dirent_hash(const char *name, u_int len)
static __inline off_t
tmpfs_dirent_cookie(struct tmpfs_dirent *de)
{
if (de == NULL)
return (TMPFS_DIRCOOKIE_EOF);
MPASS(de->td_cookie >= TMPFS_DIRCOOKIE_MIN);
return (de->td_cookie);
@ -1155,6 +1158,15 @@ tmpfs_dir_getdents(struct tmpfs_node *node, struct uio *uio, int cnt,
TMPFS_VALIDATE_DIR(node);
off = 0;
/*
* Lookup the node from the current offset. The starting offset of
* 0 will lookup both '.' and '..', and then the first real entry,
* or EOF if there are none. Then find all entries for the dir that
* fit into the buffer. Once no more entries are found (de == NULL),
* the offset is set to TMPFS_DIRCOOKIE_EOF, which will cause the next
* call to return 0.
*/
switch (uio->uio_offset) {
case TMPFS_DIRCOOKIE_DOT:
error = tmpfs_dir_getdotdent(node, uio);
@ -1168,12 +1180,10 @@ tmpfs_dir_getdents(struct tmpfs_node *node, struct uio *uio, int cnt,
if (error != 0)
return (error);
de = tmpfs_dir_first(node, &dc);
if (de == NULL)
uio->uio_offset = TMPFS_DIRCOOKIE_EOF;
else
uio->uio_offset = tmpfs_dirent_cookie(de);
if (cnt != 0)
cookies[(*ncookies)++] = off = uio->uio_offset;
/* EOF. */
if (de == NULL)
return (0);
break;
@ -1252,9 +1262,6 @@ tmpfs_dir_getdents(struct tmpfs_node *node, struct uio *uio, int cnt,
if (error == 0) {
de = tmpfs_dir_next(node, &dc);
if (cnt != 0) {
if (de == NULL)
off = TMPFS_DIRCOOKIE_EOF;
else
off = tmpfs_dirent_cookie(de);
MPASS(*ncookies < cnt);
cookies[(*ncookies)++] = off;
@ -1263,12 +1270,8 @@ tmpfs_dir_getdents(struct tmpfs_node *node, struct uio *uio, int cnt,
} while (error == 0 && uio->uio_resid > 0 && de != NULL);
/* Update the offset and cache. */
if (cnt == 0) {
if (de == NULL)
off = TMPFS_DIRCOOKIE_EOF;
else
if (cnt == 0)
off = tmpfs_dirent_cookie(de);
}
uio->uio_offset = off;
node->tn_dir.tn_readdir_lastn = off;