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Commit f8489128 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
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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: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 69964ea4

fs/ext4/extents.c

+26 −9
Original line number Diff line number Diff line
@@ -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 @@ static int ext4_ext_search_right(struct inode *inode, 
			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 @@ static int ext4_ext_search_right(struct inode *inode, 
	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 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start, 
				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;

			}

include/linux/jbd_common.h

+2 −0
Original line number Diff line number Diff line
@@ -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)

{