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Date: Fri, 7 Apr 2023 20:06:44 +0800
From: JunChao Sun <sunjunchao2870@...il.com>
To: linux-ext4@...r.kernel.org, linux-doc@...r.kernel.org
Cc: tytso@....edu, jun.nie@...aro.org
Subject: Re: [PATCH v2] ext4: fix performance issue of xattr when expanding inode
Friendly ping...
JunChao Sun <sunjunchao2870@...il.com> 于2023年4月2日周日 09:30写道：
>
> Currently ext4 will delete ea entry from ibody and recreate ea entry
> which store the same value when expanding inode. The main performance
> issue is caused by the fact that ext4 will destroy and recreate the
> ea inode, and such behavior is redundant.
>
> The patch is a bit ugly, because ext4_xattr_set_entry() contains the
> creating,deleting,replacing of xattr without external intervention,
> this looks good. But the movement of ea entry from ibody to block
> breaks this, so add an argument for ext4_xattr_set_entry() for this
> break, and then ext4_xattr_block_set() will reuse the ea_inode instead
> of recreating an ea_inode which store the same value.
>
> Signed-off-by: JunChao Sun <sunjunchao2870@...il.com>
> ---
> fs/ext4/xattr.c | 99 ++++++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 81 insertions(+), 18 deletions(-)
>
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 767454d74cd6..439581e630d4 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -1634,7 +1634,7 @@ static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
> static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
> struct ext4_xattr_search *s,
> handle_t *handle, struct inode *inode,
> - bool is_block)
> + bool is_block, struct inode *mv_ea_inode)
> {
> struct ext4_xattr_entry *last, *next;
> struct ext4_xattr_entry *here = s->here;
> @@ -1727,7 +1727,7 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
> goto out;
> }
> }
> - if (i->value && in_inode) {
> + if (i->value && in_inode && !mv_ea_inode) {
> WARN_ON_ONCE(!i->value_len);
>
> ret = ext4_xattr_inode_alloc_quota(inode, i->value_len);
> @@ -1819,7 +1819,9 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
>
> if (i->value) {
> /* Insert new value. */
> - if (in_inode) {
> + if (in_inode && mv_ea_inode) {
> + here->e_value_inum = cpu_to_le32(mv_ea_inode->i_ino);
> + } else if (in_inode) {
> here->e_value_inum = cpu_to_le32(new_ea_inode->i_ino);
> } else if (i->value_len) {
> void *val = s->base + min_offs - new_size;
> @@ -1838,7 +1840,7 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
> }
>
> update_hash:
> - if (i->value) {
> + if (i->value && !mv_ea_inode) {
> __le32 hash = 0;
>
> /* Entry hash calculation. */
> @@ -1922,7 +1924,7 @@ ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
> static int
> ext4_xattr_block_set(handle_t *handle, struct inode *inode,
> struct ext4_xattr_info *i,
> - struct ext4_xattr_block_find *bs)
> + struct ext4_xattr_block_find *bs, struct inode *mv_ea_inode)
> {
> struct super_block *sb = inode->i_sb;
> struct buffer_head *new_bh = NULL;
> @@ -1972,7 +1974,7 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
> }
> ea_bdebug(bs->bh, "modifying in-place");
> error = ext4_xattr_set_entry(i, s, handle, inode,
> - true /* is_block */);
> + true /* is_block */, NULL);
> ext4_xattr_block_csum_set(inode, bs->bh);
> unlock_buffer(bs->bh);
> if (error == -EFSCORRUPTED)
> @@ -2040,7 +2042,7 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
> s->end = s->base + sb->s_blocksize;
> }
>
> - error = ext4_xattr_set_entry(i, s, handle, inode, true /* is_block */);
> + error = ext4_xattr_set_entry(i, s, handle, inode, true /* is_block */, mv_ea_inode);
> if (error == -EFSCORRUPTED)
> goto bad_block;
> if (error)
> @@ -2286,7 +2288,7 @@ int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
> if (!EXT4_INODE_HAS_XATTR_SPACE(inode))
> return -ENOSPC;
>
> - error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */);
> + error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */, NULL);
> if (error)
> return error;
> header = IHDR(inode, ext4_raw_inode(&is->iloc));
> @@ -2429,7 +2431,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
> if (!is.s.not_found)
> error = ext4_xattr_ibody_set(handle, inode, &i, &is);
> else if (!bs.s.not_found)
> - error = ext4_xattr_block_set(handle, inode, &i, &bs);
> + error = ext4_xattr_block_set(handle, inode, &i, &bs, NULL);
> } else {
> error = 0;
> /* Xattr value did not change? Save us some work and bail out */
> @@ -2446,7 +2448,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
> error = ext4_xattr_ibody_set(handle, inode, &i, &is);
> if (!error && !bs.s.not_found) {
> i.value = NULL;
> - error = ext4_xattr_block_set(handle, inode, &i, &bs);
> + error = ext4_xattr_block_set(handle, inode, &i, &bs, NULL);
> } else if (error == -ENOSPC) {
> if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
> brelse(bs.bh);
> @@ -2455,7 +2457,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
> if (error)
> goto cleanup;
> }
> - error = ext4_xattr_block_set(handle, inode, &i, &bs);
> + error = ext4_xattr_block_set(handle, inode, &i, &bs, NULL);
> if (!error && !is.s.not_found) {
> i.value = NULL;
> error = ext4_xattr_ibody_set(handle, inode, &i,
> @@ -2615,6 +2617,10 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
> .in_inode = !!entry->e_value_inum,
> };
> struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
> + struct ext4_xattr_entry *here = NULL, *last = NULL, *next = NULL;
> + struct inode *old_ea_inode = NULL;
> + size_t name_size = EXT4_XATTR_LEN(entry->e_name_len);
> + size_t min_offs;
> int error;
>
> is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
> @@ -2660,20 +2666,76 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
>
> i.value = buffer;
> i.value_len = value_size;
> + here = is->s.here;
> + last = is->s.first;
> + min_offs = is->s.end - is->s.base;
> + /* Compute min_offs and last entry */
> + for (; !IS_LAST_ENTRY(last); last = next) {
> + next = EXT4_XATTR_NEXT(last);
> + if ((void *)next >= is->s.end) {
> + EXT4_ERROR_INODE(inode, "corrupted xattr entries");
> + error = -EFSCORRUPTED;
> + goto out;
> + }
> + if (!last->e_value_inum && last->e_value_size) {
> + size_t offs = le16_to_cpu(last->e_value_offs);
> +
> + if (offs < min_offs)
> + min_offs = offs;
> + }
> + }
> +
> + /* Remove the name in ibody */
> + last = ENTRY((void *)last - name_size);
> + memmove(here, (void *)here + name_size,
> + (void *)last - (void *)here + sizeof(__u32));
> + memset(last, 0, name_size);
> +
> + /* Get the ea_inode which store the old value */
> + if (here->e_value_inum) {
> + error = ext4_xattr_inode_iget(inode,
> + le32_to_cpu(here->e_value_inum),
> + le32_to_cpu(here->e_hash),
> + &old_ea_inode);
> + if (error) {
> + old_ea_inode = NULL;
> + goto out;
> + }
> + } else if (here->e_value_size) {
> + /* Remove the old value in ibody */
> + void *first_val = is->s.base + min_offs;
> + void *rm_val = is->s.base + le16_to_cpu(here->e_value_offs);
> + size_t rm_size = EXT4_XATTR_SIZE(le32_to_cpu(here->e_value_size));
> + size_t offs = le16_to_cpu(here->e_value_offs);
> +
> + memmove(first_val + rm_size, first_val, rm_val - first_val);
> + memset(first_val, 0, rm_size);
> + min_offs += rm_size;
> +
> + /* Adjust all value offsets */
> + last = is->s.first;
> + while (!IS_LAST_ENTRY(last)) {
> + size_t o = le16_to_cpu(last->e_value_offs);
> +
> + if (!last->e_value_inum &&
> + last->e_value_size && o < offs)
> + last->e_value_offs = cpu_to_le16(o + rm_size);
> + last = EXT4_XATTR_NEXT(last);
> + }
> + }
> +
> error = ext4_xattr_block_find(inode, &i, bs);
> if (error)
> goto out;
>
> - /* Move ea entry from the inode into the block */
> - error = ext4_xattr_block_set(handle, inode, &i, bs);
> + /*
> + * Move ea entry from the inode into the block, and do not need to
> + * recreate an ea_inode that store the same value.
> + */
> + error = ext4_xattr_block_set(handle, inode, &i, bs, old_ea_inode);
> if (error)
> goto out;
>
> - /* Remove the chosen entry from the inode */
> - i.value = NULL;
> - i.value_len = 0;
> - error = ext4_xattr_ibody_set(handle, inode, &i, is);
> -
> out:
> kfree(b_entry_name);
> if (entry->e_value_inum && buffer)
> @@ -2684,6 +2746,7 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
> brelse(bs->bh);
> kfree(is);
> kfree(bs);
> + iput(old_ea_inode);
>
> return error;
> }
> --
> 2.17.1
>
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