[PATCH 5/7] repair: don't duplicate names in phase 6

Dave Chinner
2021-03-19T01:34:54Z

From: Dave Chinner <dchinner@redhat.com>

The name hash in phase 6 is constructed by using names that point
directly into the directory buffers. Hence before the buffers can be
released, the constructed name hash has to duplicate all those names
into meory it owns via dir_hash_dup_names().

Given that the structure that holds the name is dynamically
allocated, it makes no sense to store a pointer to the name
dir_hash_add() and then later have dynamically allocate the name.

Extend the name hash allocation to contain space for the name
itself, and copy the name into the name hash structure in
dir_hash_add(). This allows us to get rid of dir_hash_dup_names(),
and the directory checking code no longer needs to hold all the
directory buffers in memory until the entire directory walk is
complete and the names duplicated.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
repair/phase6.c | 101 ++++++++++++++----------------------------------
1 file changed, 29 insertions(+), 72 deletions(-)

diff --git a/repair/phase6.c b/repair/phase6.c
index 85abea29250a..440b6a2982df 100644
--- a/repair/phase6.c
+++ b/repair/phase6.c
@@ -72,7 +72,7 @@ typedef struct dir_hash_ent {
struct dir_hash_ent *nextbyorder; /* next in order added */
xfs_dahash_t hashval; /* hash value of name */
uint32_t address; /* offset of data entry */
- xfs_ino_t inum; /* inode num of entry */
+ xfs_ino_t inum; /* inode num of entry */
short junkit; /* name starts with / */
short seen; /* have seen leaf entry */
struct xfs_name name;
@@ -80,7 +80,6 @@ typedef struct dir_hash_ent {

typedef struct dir_hash_tab {
int size; /* size of hash tables */
- int names_duped; /* 1 = ent names malloced */
dir_hash_ent_t *first; /* ptr to first added entry */
dir_hash_ent_t *last; /* ptr to last added entry */
dir_hash_ent_t **byhash; /* ptr to name hash buckets */
@@ -171,8 +170,6 @@ dir_hash_add(
short junk;
struct xfs_name xname;

- ASSERT(!hashtab->names_duped);
-
xname.name = name;
xname.len = namelen;
xname.type = ftype;
@@ -199,7 +196,12 @@ dir_hash_add(
}
}

- if ((p = malloc(sizeof(*p))) == NULL)
+ /*
+ * Allocate enough space for the hash entry and the name in a single
+ * allocation so we can store our own copy of the name for later use.
+ */
+ p = calloc(1, sizeof(*p) + namelen + 1);
+ if (!p)
do_error(_("malloc failed in dir_hash_add (%zu bytes)\n"),
sizeof(*p));

@@ -220,7 +222,12 @@ dir_hash_add(
p->address = addr;
p->inum = inum;
p->seen = 0;
- p->name = xname;
+
+ /* Set up the name in the region trailing the hash entry. */
+ memcpy(p + 1, name, namelen);
+ p->name.name = (const unsigned char *)(p + 1);
+ p->name.len = namelen;
+ p->name.type = ftype;

return !dup;
}
@@ -287,8 +294,6 @@ dir_hash_done(
for (i = 0; i < hashtab->size; i++) {
for (p = hashtab->byaddr[i]; p; p = n) {
n = p->nextbyaddr;
- if (hashtab->names_duped)
- free((void *)p->name.name);
free(p);
}
}
@@ -385,27 +390,6 @@ dir_hash_see_all(
return j == stale ? DIR_HASH_CK_OK : DIR_HASH_CK_BADSTALE;
}

-/*
- * Convert name pointers into locally allocated memory.
- * This must only be done after all the entries have been added.
- */
-static void
-dir_hash_dup_names(dir_hash_tab_t *hashtab)
-{
- unsigned char *name;
- dir_hash_ent_t *p;
-
- if (hashtab->names_duped)
- return;
-
- for (p = hashtab->first; p; p = p->nextbyorder) {
- name = malloc(p->name.len);
- memcpy(name, p->name.name, p->name.len);
- p->name.name = name;
- }
- hashtab->names_duped = 1;
-}
-
/*
* Given a block number in a fork, return the next valid block number (not a
* hole). If this is the last block number then NULLFILEOFF is returned.
@@ -1383,6 +1367,7 @@ dir2_kill_block(
res_failed(error);
libxfs_trans_ijoin(tp, ip, 0);
libxfs_trans_bjoin(tp, bp);
+ libxfs_trans_bhold(tp, bp);
memset(&args, 0, sizeof(args));
args.dp = ip;
args.trans = tp;
@@ -1414,7 +1399,7 @@ longform_dir2_entry_check_data(
int *need_dot,
ino_tree_node_t *current_irec,
int current_ino_offset,
- struct xfs_buf **bpp,
+ struct xfs_buf *bp,
dir_hash_tab_t *hashtab,
freetab_t **freetabp,
xfs_dablk_t da_bno,
@@ -1422,7 +1407,6 @@ longform_dir2_entry_check_data(
{
xfs_dir2_dataptr_t addr;
xfs_dir2_leaf_entry_t *blp;
- struct xfs_buf *bp;
xfs_dir2_block_tail_t *btp;
struct xfs_dir2_data_hdr *d;
xfs_dir2_db_t db;
@@ -1453,7 +1437,6 @@ longform_dir2_entry_check_data(
};

- bp = *bpp;
d = bp->b_addr;
ptr = (char *)d + mp->m_dir_geo->data_entry_offset;
nbad = 0;
@@ -1554,10 +1537,8 @@ longform_dir2_entry_check_data(
dir2_kill_block(mp, ip, da_bno, bp);
} else {
do_warn(_("would junk block\n"));
- libxfs_buf_relse(bp);
}
freetab->ents[db].v = NULLDATAOFF;
- *bpp = NULL;
return;
}

@@ -2215,17 +2196,15 @@ longform_dir2_entry_check(xfs_mount_t *mp,
int ino_offset,
dir_hash_tab_t *hashtab)
{
- struct xfs_buf **bplist;
+ struct xfs_buf *bp;
xfs_dablk_t da_bno;
freetab_t *freetab;
- int num_bps;
int i;
int isblock;
int isleaf;
xfs_fileoff_t next_da_bno;
int seeval;
int fixit = 0;
- xfs_dir2_db_t db;
struct xfs_da_args args;

*need_dot = 1;
@@ -2242,11 +2221,6 @@ longform_dir2_entry_check(xfs_mount_t *mp,
freetab->ents[i].v = NULLDATAOFF;
freetab->ents[i].s = 0;
}
- num_bps = freetab->naents;
- bplist = calloc(num_bps, sizeof(struct xfs_buf*));
- if (!bplist)
- do_error(_("calloc failed in %s (%zu bytes)\n"),
- __func__, num_bps * sizeof(struct xfs_buf*));

/* is this a block, leaf, or node directory? */
args.dp = ip;
@@ -2275,28 +2249,12 @@ longform_dir2_entry_check(xfs_mount_t *mp,
break;
}

- db = xfs_dir2_da_to_db(mp->m_dir_geo, da_bno);
- if (db >= num_bps) {
- int last_size = num_bps;
-
- /* more data blocks than expected */
- num_bps = db + 1;
- bplist = realloc(bplist, num_bps * sizeof(struct xfs_buf*));
- if (!bplist)
- do_error(_("realloc failed in %s (%zu bytes)\n"),
- __func__,
- num_bps * sizeof(struct xfs_buf*));
- /* Initialize the new elements */
- for (i = last_size; i < num_bps; i++)
- bplist[i] = NULL;
- }
-
if (isblock)
ops = &xfs_dir3_block_buf_ops;
else
ops = &xfs_dir3_data_buf_ops;

- error = dir_read_buf(ip, da_bno, &bplist[db], ops, &fixit);
+ error = dir_read_buf(ip, da_bno, &bp, ops, &fixit);
if (error) {
do_warn(
_("can't read data block %u for directory inode %" PRIu64 " error %d\n"),
@@ -2316,21 +2274,25 @@ longform_dir2_entry_check(xfs_mount_t *mp,
}

/* check v5 metadata */
- d = bplist[db]->b_addr;
+ d = bp->b_addr;
if (be32_to_cpu(d->magic) == XFS_DIR3_BLOCK_MAGIC ||
be32_to_cpu(d->magic) == XFS_DIR3_DATA_MAGIC) {
- struct xfs_buf *bp = bplist[db];
-
error = check_dir3_header(mp, bp, ino);
if (error) {
fixit++;
+ if (isblock)
+ goto out_fix;
continue;
}
}

longform_dir2_entry_check_data(mp, ip, num_illegal, need_dot,
- irec, ino_offset, &bplist[db], hashtab,
+ irec, ino_offset, bp, hashtab,
&freetab, da_bno, isblock);
+ if (isblock)
+ break;
+
+ libxfs_buf_relse(bp);
}
fixit |= (*num_illegal != 0) || dir2_is_badino(ino) || *need_dot;

@@ -2341,7 +2303,7 @@ longform_dir2_entry_check(xfs_mount_t *mp,
xfs_dir2_block_tail_t *btp;
xfs_dir2_leaf_entry_t *blp;

- block = bplist[0]->b_addr;
+ block = bp->b_addr;
btp = xfs_dir2_block_tail_p(mp->m_dir_geo, block);
blp = xfs_dir2_block_leaf_p(btp);
seeval = dir_hash_see_all(hashtab, blp,
@@ -2358,11 +2320,10 @@ longform_dir2_entry_check(xfs_mount_t *mp,
}
}
out_fix:
+ if (isblock && bp)
+ libxfs_buf_relse(bp);
+
if (!no_modify && (fixit || dotdot_update)) {
- dir_hash_dup_names(hashtab);
- for (i = 0; i < num_bps; i++)
- if (bplist[i])
- libxfs_buf_relse(bplist[i]);
longform_dir2_rebuild(mp, ino, ip, irec, ino_offset, hashtab);
*num_illegal = 0;
*need_dot = 0;
@@ -2370,12 +2331,8 @@ out_fix:
if (fixit || dotdot_update)
do_warn(
_("would rebuild directory inode %" PRIu64 "\n"), ino);
- for (i = 0; i < num_bps; i++)
- if (bplist[i])
- libxfs_buf_relse(bplist[i]);
}

- free(bplist);
free(freetab);
}

--
2.30.1