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ext4: create a new BH_Verified flag to avoid unnecessary metadata validation 

Create a new BH_Verified flag to indicate that we've verified all the
data in a buffer_head for correctness.  This allows us to bypass
expensive verification steps when they are not necessary without
missing them when they are.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Darrick J. Wong 2012-04-29 18:21:10 -04:00 committed by Theodore Ts'o
parent 69964ea4c7
commit f84891289e
2 changed files with 28 additions and 9 deletions
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35
fs/ext4/extents.c
View File

@ -412,6 +412,26 @@ int ext4_ext_check_inode(struct inode *inode)
return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode));
}
static int __ext4_ext_check_block(const char *function, unsigned int line,
struct inode *inode,
struct ext4_extent_header *eh,
int depth,
struct buffer_head *bh)
{
int ret;
if (buffer_verified(bh))
return 0;
ret = ext4_ext_check(inode, eh, depth);
if (ret)
return ret;
set_buffer_verified(bh);
return ret;
}
#define ext4_ext_check_block(inode, eh, depth, bh) \
__ext4_ext_check_block(__func__, __LINE__, inode, eh, depth, bh)
#ifdef EXT_DEBUG
static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
{
@ -668,8 +688,6 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
i = depth;
/* walk through the tree */
while (i) {
int need_to_validate = 0;
ext_debug("depth %d: num %d, max %d\n",
ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
@ -688,8 +706,6 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
put_bh(bh);
goto err;
}
/* validate the extent entries */
need_to_validate = 1;
}
eh = ext_block_hdr(bh);
ppos++;
@ -703,7 +719,7 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
path[ppos].p_hdr = eh;
i--;
if (need_to_validate && ext4_ext_check(inode, eh, i))
if (ext4_ext_check_block(inode, eh, i, bh))
goto err;
}
@ -1344,7 +1360,8 @@ got_index:
return -EIO;
eh = ext_block_hdr(bh);
/* subtract from p_depth to get proper eh_depth */
if (ext4_ext_check(inode, eh, path->p_depth - depth)) {
if (ext4_ext_check_block(inode, eh,
path->p_depth - depth, bh)) {
put_bh(bh);
return -EIO;
}
@ -1357,7 +1374,7 @@ got_index:
if (bh == NULL)
return -EIO;
eh = ext_block_hdr(bh);
if (ext4_ext_check(inode, eh, path->p_depth - depth)) {
if (ext4_ext_check_block(inode, eh, path->p_depth - depth, bh)) {
put_bh(bh);
return -EIO;
}
@ -2644,8 +2661,8 @@ cont:
err = -EIO;
break;
}
if (ext4_ext_check(inode, ext_block_hdr(bh),
depth - i - 1)) {
if (ext4_ext_check_block(inode, ext_block_hdr(bh),
depth - i - 1, bh)) {
err = -EIO;
break;
}

2
include/linux/jbd_common.h
View File

@ -12,6 +12,7 @@ enum jbd_state_bits {
BH_State, /* Pins most journal_head state */
BH_JournalHead, /* Pins bh->b_private and jh->b_bh */
BH_Unshadow, /* Dummy bit, for BJ_Shadow wakeup filtering */
BH_Verified, /* Metadata block has been verified ok */
BH_JBDPrivateStart, /* First bit available for private use by FS */
};
@ -24,6 +25,7 @@ TAS_BUFFER_FNS(Revoked, revoked)
BUFFER_FNS(RevokeValid, revokevalid)
TAS_BUFFER_FNS(RevokeValid, revokevalid)
BUFFER_FNS(Freed, freed)
BUFFER_FNS(Verified, verified)
static inline struct buffer_head *jh2bh(struct journal_head *jh)
{