2021-04-07 20:28:11

by Andreas Dilger

[permalink] [raw]
Subject: [PATCH] ext2fs: avoid re-reading inode multiple times

Reduce the number of times that the inode is read from storage.
Factor ext2fs_xattrs_read() into a new ext2fs_xattrs_read_inode()
function that can accept an in-memory inode, and call that from
within ext2fs_xattrs_read() and in e2fsck_pass1() when the inode
is already available.

Similarly, in e2fsck_pass4() avoid re-reading the inode multiple
times in disconnect_inode(), check_ea_inode(), and in the main
function body if possible.

Signed-off-by: Andreas Dilger <[email protected]>
---
e2fsck/pass1.c | 9 ++++---
e2fsck/pass4.c | 47 +++++++++++++++++++++--------------
lib/ext2fs/ext2fs.h | 2 ++
lib/ext2fs/ext_attr.c | 57 +++++++++++++++++++++++++------------------
4 files changed, 70 insertions(+), 45 deletions(-)

diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 9d430895..e22135de 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -911,6 +911,7 @@ static void reserve_block_for_lnf_repair(e2fsck_t ctx)
}

static errcode_t get_inline_data_ea_size(ext2_filsys fs, ext2_ino_t ino,
+ struct ext2_inode *inode,
size_t *sz)
{
void *p;
@@ -921,7 +922,8 @@ static errcode_t get_inline_data_ea_size(ext2_filsys fs, ext2_ino_t ino,
if (retval)
return retval;

- retval = ext2fs_xattrs_read(handle);
+ retval = ext2fs_xattrs_read_inode(handle,
+ (struct ext2_inode_large *)inode);
if (retval)
goto err;

@@ -1508,7 +1510,8 @@ void e2fsck_pass1(e2fsck_t ctx)
(ino >= EXT2_FIRST_INODE(fs->super))) {
size_t size = 0;

- pctx.errcode = get_inline_data_ea_size(fs, ino, &size);
+ pctx.errcode = get_inline_data_ea_size(fs, ino, inode,
+ &size);
if (!pctx.errcode &&
fix_problem(ctx, PR_1_INLINE_DATA_FEATURE, &pctx)) {
ext2fs_set_feature_inline_data(sb);
@@ -1531,7 +1534,7 @@ void e2fsck_pass1(e2fsck_t ctx)
flags = fs->flags;
if (failed_csum)
fs->flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;
- err = get_inline_data_ea_size(fs, ino, &size);
+ err = get_inline_data_ea_size(fs, ino, inode, &size);
fs->flags = (flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) |
(fs->flags & ~EXT2_FLAG_IGNORE_CSUM_ERRORS);

diff --git a/e2fsck/pass4.c b/e2fsck/pass4.c
index 8c2d2f1f..6e9e8fe8 100644
--- a/e2fsck/pass4.c
+++ b/e2fsck/pass4.c
@@ -26,7 +26,7 @@
* This subroutine returns 1 then the caller shouldn't bother with the
* rest of the pass 4 tests.
*/
-static int disconnect_inode(e2fsck_t ctx, ext2_ino_t i,
+static int disconnect_inode(e2fsck_t ctx, ext2_ino_t i, ext2_ino_t *last_ino,
struct ext2_inode_large *inode)
{
ext2_filsys fs = ctx->fs;
@@ -34,9 +34,12 @@ static int disconnect_inode(e2fsck_t ctx, ext2_ino_t i,
__u32 eamagic = 0;
int extra_size = 0;

- e2fsck_read_inode_full(ctx, i, EXT2_INODE(inode),
- EXT2_INODE_SIZE(fs->super),
- "pass4: disconnect_inode");
+ if (*last_ino != i) {
+ e2fsck_read_inode_full(ctx, i, EXT2_INODE(inode),
+ EXT2_INODE_SIZE(fs->super),
+ "pass4: disconnect_inode");
+ *last_ino = i;
+ }
if (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE)
extra_size = inode->i_extra_isize;

@@ -75,6 +78,7 @@ static int disconnect_inode(e2fsck_t ctx, ext2_ino_t i,
if (fix_problem(ctx, PR_4_UNATTACHED_INODE, &pctx)) {
if (e2fsck_reconnect_file(ctx, i))
ext2fs_unmark_valid(fs);
+ *last_ino = 0;
} else {
/*
* If we don't attach the inode, then skip the
@@ -87,20 +91,22 @@ static int disconnect_inode(e2fsck_t ctx, ext2_ino_t i,
return 0;
}

-static void check_ea_inode(e2fsck_t ctx, ext2_ino_t i,
+/*
+ * This function is called when link_counted is zero. So this may not be
+ * an xattr inode at all. Return immediately if EA_INODE flag is not set.
+ */
+static void check_ea_inode(e2fsck_t ctx, ext2_ino_t i, ext2_ino_t *last_ino,
struct ext2_inode_large *inode, __u16 *link_counted)
{
__u64 actual_refs = 0;
__u64 ref_count;

- /*
- * This function is called when link_counted is zero. So this may not
- * be an xattr inode at all. Return immediately if EA_INODE flag is not
- * set.
- */
- e2fsck_read_inode_full(ctx, i, EXT2_INODE(inode),
- EXT2_INODE_SIZE(ctx->fs->super),
- "pass4: check_ea_inode");
+ if (*last_ino != i) {
+ e2fsck_read_inode_full(ctx, i, EXT2_INODE(inode),
+ EXT2_INODE_SIZE(ctx->fs->super),
+ "pass4: check_ea_inode");
+ *last_ino = i;
+ }
if (!(inode->i_flags & EXT4_EA_INODE_FL))
return;

@@ -180,7 +186,8 @@ void e2fsck_pass4(e2fsck_t ctx)
inode = e2fsck_allocate_memory(ctx, inode_size, "scratch inode");

/* Protect loop from wrap-around if s_inodes_count maxed */
- for (i=1; i <= fs->super->s_inodes_count && i > 0; i++) {
+ for (i = 1; i <= fs->super->s_inodes_count && i > 0; i++) {
+ ext2_ino_t last_ino = 0;
int isdir;

if (ctx->flags & E2F_FLAG_SIGNAL_MASK)
@@ -210,7 +217,7 @@ void e2fsck_pass4(e2fsck_t ctx)
* check_ea_inode() will update link_counted if
* necessary.
*/
- check_ea_inode(ctx, i, inode, &link_counted);
+ check_ea_inode(ctx, i, &last_ino, inode, &link_counted);
}

if (link_counted == 0) {
@@ -219,7 +226,7 @@ void e2fsck_pass4(e2fsck_t ctx)
fs->blocksize, "bad_inode buffer");
if (e2fsck_process_bad_inode(ctx, 0, i, buf))
continue;
- if (disconnect_inode(ctx, i, inode))
+ if (disconnect_inode(ctx, i, &last_ino, inode))
continue;
ext2fs_icount_fetch(ctx->inode_link_info, i,
&link_count);
@@ -239,8 +246,12 @@ void e2fsck_pass4(e2fsck_t ctx)
if (link_counted != link_count) {
int fix_nlink = 0;

- e2fsck_read_inode_full(ctx, i, EXT2_INODE(inode),
- inode_size, "pass4");
+ if (last_ino != i) {
+ e2fsck_read_inode_full(ctx, i,
+ EXT2_INODE(inode),
+ inode_size, "pass4");
+ last_ino = i;
+ }
pctx.ino = i;
pctx.inode = EXT2_INODE(inode);
if ((link_count != inode->i_links_count) && !isdir &&
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index df150f00..948eb0b2 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1276,6 +1276,8 @@ extern errcode_t ext2fs_adjust_ea_refcount3(ext2_filsys fs, blk64_t blk,
ext2_ino_t inum);
errcode_t ext2fs_xattrs_write(struct ext2_xattr_handle *handle);
errcode_t ext2fs_xattrs_read(struct ext2_xattr_handle *handle);
+errcode_t ext2fs_xattrs_read_inode(struct ext2_xattr_handle *handle,
+ struct ext2_inode_large *inode);
errcode_t ext2fs_xattrs_iterate(struct ext2_xattr_handle *h,
int (*func)(char *name, char *value,
size_t value_len, void *data),
diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
index 148fae5b..1933ca19 100644
--- a/lib/ext2fs/ext_attr.c
+++ b/lib/ext2fs/ext_attr.c
@@ -985,9 +985,11 @@ static void xattrs_free_keys(struct ext2_xattr_handle *h)
h->ibody_count = 0;
}

-errcode_t ext2fs_xattrs_read(struct ext2_xattr_handle *handle)
+/* fetch xattrs from an already-loaded inode */
+errcode_t ext2fs_xattrs_read_inode(struct ext2_xattr_handle *handle,
+ struct ext2_inode_large *inode)
{
- struct ext2_inode_large *inode;
+
struct ext2_ext_attr_header *header;
__u32 ea_inode_magic;
unsigned int storage_size;
@@ -997,18 +999,6 @@ errcode_t ext2fs_xattrs_read(struct ext2_xattr_handle *handle)
errcode_t err;

EXT2_CHECK_MAGIC(handle, EXT2_ET_MAGIC_EA_HANDLE);
- i = EXT2_INODE_SIZE(handle->fs->super);
- if (i < sizeof(*inode))
- i = sizeof(*inode);
- err = ext2fs_get_memzero(i, &inode);
- if (err)
- return err;
-
- err = ext2fs_read_inode_full(handle->fs, handle->ino,
- (struct ext2_inode *)inode,
- EXT2_INODE_SIZE(handle->fs->super));
- if (err)
- goto out;

xattrs_free_keys(handle);

@@ -1044,7 +1034,7 @@ errcode_t ext2fs_xattrs_read(struct ext2_xattr_handle *handle)

read_ea_block:
/* Look for EA in a separate EA block */
- blk = ext2fs_file_acl_block(handle->fs, (struct ext2_inode *)inode);
+ blk = ext2fs_file_acl_block(handle->fs, EXT2_INODE(inode));
if (blk != 0) {
if ((blk < handle->fs->super->s_first_data_block) ||
(blk >= ext2fs_blocks_count(handle->fs->super))) {
@@ -1075,20 +1065,39 @@ read_ea_block:
err = read_xattrs_from_buffer(handle, inode,
(struct ext2_ext_attr_entry *) start,
storage_size, block_buf);
- if (err)
- goto out3;
-
- ext2fs_free_mem(&block_buf);
}

- ext2fs_free_mem(&block_buf);
- ext2fs_free_mem(&inode);
- return 0;
-
out3:
- ext2fs_free_mem(&block_buf);
+ if (block_buf)
+ ext2fs_free_mem(&block_buf);
+out:
+ return err;
+}
+
+errcode_t ext2fs_xattrs_read(struct ext2_xattr_handle *handle)
+{
+ struct ext2_inode_large *inode;
+ size_t inode_size = EXT2_INODE_SIZE(handle->fs->super);
+ errcode_t err;
+
+ EXT2_CHECK_MAGIC(handle, EXT2_ET_MAGIC_EA_HANDLE);
+
+ if (inode_size < sizeof(*inode))
+ inode_size = sizeof(*inode);
+ err = ext2fs_get_memzero(inode_size, &inode);
+ if (err)
+ return err;
+
+ err = ext2fs_read_inode_full(handle->fs, handle->ino, EXT2_INODE(inode),
+ EXT2_INODE_SIZE(handle->fs->super));
+ if (err)
+ goto out;
+
+ err = ext2fs_xattrs_read_inode(handle, inode);
+
out:
ext2fs_free_mem(&inode);
+
return err;
}

--
2.25.1