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Date: Wed, 14 Jun 2017 18:11:10 -0600
From: Andreas Dilger <adilger@...ger.ca>
To: Tahsin Erdogan <tahsin@...gle.com>
Cc: Jan Kara <jack@...e.com>, Theodore Ts'o <tytso@....edu>,
Dave Kleikamp <shaggy@...nel.org>,
Alexander Viro <viro@...iv.linux.org.uk>,
Mark Fasheh <mfasheh@...sity.com>,
Joel Becker <jlbec@...lplan.org>, Jens Axboe <axboe@...com>,
Deepa Dinamani <deepa.kernel@...il.com>,
Mike Christie <mchristi@...hat.com>,
Fabian Frederick <fabf@...net.be>,
linux-ext4 <linux-ext4@...r.kernel.org>,
lkml <linux-kernel@...r.kernel.org>,
jfs-discussion@...ts.sourceforge.net,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
ocfs2-devel@....oracle.com, reiserfs-devel@...r.kernel.org
Subject: Re: [PATCH v2 26/28] ext4: cleanup transaction restarts during inode
deletion
On Jun 14, 2017, at 8:17 AM, Tahsin Erdogan <tahsin@...gle.com> wrote:
>
> During inode deletion, journal credits that will be needed are hard to
> determine, that is why we have journal extend/restart calls in several
> places. Whenever a transaction is restarted, filesystem must be in a
> consistent state because there is no atomicity guarantee beyond a
> restart call.
>
> Add ext4_xattr_ensure_credits() helper function which takes care of
> journal extend/restart logic. It also handles getting jbd2 write access
> and dirty metadata calls. This function is called at every iteration of
> handling an ea_inode reference.
Another option that might be less complex is to just add the xattr inodes
to the orphan list in the main transaction (which should be a fixed number
of credits), and then truncate/unlink the xattr inodes after the main
transaction has completed rather than making the transactions arbitrarily
large. At one point we even had a separate unlink thread to handle this
in the background to reduce the unlink latency for very large files, which
also avoids issues with nested transactions.
Cheers, Andreas
> Signed-off-by: Tahsin Erdogan <tahsin@...gle.com>
> ---
> v2: made ext4_xattr_ensure_credits() static
>
> fs/ext4/inode.c | 66 ++++-----------
> fs/ext4/xattr.c | 257 ++++++++++++++++++++++++++++++++++++--------------------
> fs/ext4/xattr.h | 3 +-
> 3 files changed, 183 insertions(+), 143 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index cf91532765a4..4d6936f0d8a4 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -239,7 +239,11 @@ void ext4_evict_inode(struct inode *inode)
> */
> sb_start_intwrite(inode->i_sb);
>
> - handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, extra_credits);
> + if (!IS_NOQUOTA(inode))
> + extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb);
> +
> + handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
> + ext4_blocks_for_truncate(inode)+extra_credits);
> if (IS_ERR(handle)) {
> ext4_std_error(inode->i_sb, PTR_ERR(handle));
> /*
> @@ -251,36 +255,9 @@ void ext4_evict_inode(struct inode *inode)
> sb_end_intwrite(inode->i_sb);
> goto no_delete;
> }
> +
> if (IS_SYNC(inode))
> ext4_handle_sync(handle);
> -
> - /*
> - * Delete xattr inode before deleting the main inode.
> - */
> - err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array);
> - if (err) {
> - ext4_warning(inode->i_sb,
> - "couldn't delete inode's xattr (err %d)", err);
> - goto stop_handle;
> - }
> -
> - if (!IS_NOQUOTA(inode))
> - extra_credits += 2 * EXT4_QUOTA_DEL_BLOCKS(inode->i_sb);
> -
> - if (!ext4_handle_has_enough_credits(handle,
> - ext4_blocks_for_truncate(inode) + extra_credits)) {
> - err = ext4_journal_extend(handle,
> - ext4_blocks_for_truncate(inode) + extra_credits);
> - if (err > 0)
> - err = ext4_journal_restart(handle,
> - ext4_blocks_for_truncate(inode) + extra_credits);
> - if (err != 0) {
> - ext4_warning(inode->i_sb,
> - "couldn't extend journal (err %d)", err);
> - goto stop_handle;
> - }
> - }
> -
> inode->i_size = 0;
> err = ext4_mark_inode_dirty(handle, inode);
> if (err) {
> @@ -298,25 +275,17 @@ void ext4_evict_inode(struct inode *inode)
> }
> }
>
> - /*
> - * ext4_ext_truncate() doesn't reserve any slop when it
> - * restarts journal transactions; therefore there may not be
> - * enough credits left in the handle to remove the inode from
> - * the orphan list and set the dtime field.
> - */
> - if (!ext4_handle_has_enough_credits(handle, extra_credits)) {
> - err = ext4_journal_extend(handle, extra_credits);
> - if (err > 0)
> - err = ext4_journal_restart(handle, extra_credits);
> - if (err != 0) {
> - ext4_warning(inode->i_sb,
> - "couldn't extend journal (err %d)", err);
> - stop_handle:
> - ext4_journal_stop(handle);
> - ext4_orphan_del(NULL, inode);
> - sb_end_intwrite(inode->i_sb);
> - goto no_delete;
> - }
> + /* Remove xattr references. */
> + err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array,
> + extra_credits);
> + if (err) {
> + ext4_warning(inode->i_sb, "xattr delete (err %d)", err);
> + stop_handle:
> + ext4_journal_stop(handle);
> + ext4_orphan_del(NULL, inode);
> + sb_end_intwrite(inode->i_sb);
> + ext4_xattr_inode_array_free(ea_inode_array);
> + goto no_delete;
> }
>
> /*
> @@ -342,7 +311,6 @@ void ext4_evict_inode(struct inode *inode)
> ext4_clear_inode(inode);
> else
> ext4_free_inode(handle, inode);
> -
> ext4_journal_stop(handle);
> sb_end_intwrite(inode->i_sb);
> ext4_xattr_inode_array_free(ea_inode_array);
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 3ee7e2f68476..abc7d5f84e5f 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -108,6 +108,10 @@ const struct xattr_handler *ext4_xattr_handlers[] = {
> #define EXT4_GET_MB_CACHE(inode) (((struct ext4_sb_info *) \
> inode->i_sb->s_fs_info)->s_mb_cache)
>
> +static int
> +ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
> + struct inode *inode);
> +
> #ifdef CONFIG_LOCKDEP
> void ext4_xattr_inode_set_class(struct inode *ea_inode)
> {
> @@ -653,6 +657,127 @@ static void ext4_xattr_update_super_block(handle_t *handle,
> }
> }
>
> +static int ext4_xattr_ensure_credits(handle_t *handle, struct inode *inode,
> + int credits, struct buffer_head *bh,
> + bool dirty, bool block_csum)
> +{
> + int error;
> +
> + if (!ext4_handle_valid(handle))
> + return 0;
> +
> + if (handle->h_buffer_credits >= credits)
> + return 0;
> +
> + error = ext4_journal_extend(handle, credits - handle->h_buffer_credits);
> + if (!error)
> + return 0;
> + if (error < 0) {
> + ext4_warning(inode->i_sb, "Extend journal (error %d)", error);
> + return error;
> + }
> +
> + if (bh && dirty) {
> + if (block_csum)
> + ext4_xattr_block_csum_set(inode, bh);
> + error = ext4_handle_dirty_metadata(handle, NULL, bh);
> + if (error) {
> + ext4_warning(inode->i_sb, "Handle metadata (error %d)",
> + error);
> + return error;
> + }
> + }
> +
> + error = ext4_journal_restart(handle, credits);
> + if (error) {
> + ext4_warning(inode->i_sb, "Restart journal (error %d)", error);
> + return error;
> + }
> +
> + if (bh) {
> + error = ext4_journal_get_write_access(handle, bh);
> + if (error) {
> + ext4_warning(inode->i_sb,
> + "Get write access failed (error %d)",
> + error);
> + return error;
> + }
> + }
> + return 0;
> +}
> +
> +static void
> +ext4_xattr_inode_remove_all(handle_t *handle, struct inode *parent,
> + struct buffer_head *bh,
> + struct ext4_xattr_entry *first, bool block_csum,
> + struct ext4_xattr_inode_array **ea_inode_array,
> + int extra_credits)
> +{
> + struct inode *ea_inode;
> + struct ext4_xattr_entry *entry;
> + bool dirty = false;
> + unsigned int ea_ino;
> + int err;
> + int credits;
> +
> + /* One credit for dec ref on ea_inode, one for orphan list addition, */
> + credits = 2 + extra_credits;
> +
> + for (entry = first; !IS_LAST_ENTRY(entry);
> + entry = EXT4_XATTR_NEXT(entry)) {
> + if (!entry->e_value_inum)
> + continue;
> + ea_ino = le32_to_cpu(entry->e_value_inum);
> + err = ext4_xattr_inode_iget(parent, ea_ino, &ea_inode);
> + if (err)
> + continue;
> +
> + err = ext4_expand_inode_array(ea_inode_array, ea_inode);
> + if (err) {
> + ext4_warning_inode(ea_inode,
> + "Expand inode array err=%d", err);
> + iput(ea_inode);
> + continue;
> + }
> +
> + err = ext4_xattr_ensure_credits(handle, parent, credits, bh,
> + dirty, block_csum);
> + if (err) {
> + ext4_warning_inode(ea_inode, "Ensure credits err=%d",
> + err);
> + continue;
> + }
> +
> + inode_lock(ea_inode);
> + clear_nlink(ea_inode);
> + ext4_orphan_add(handle, ea_inode);
> + inode_unlock(ea_inode);
> +
> + /*
> + * Forget about ea_inode within the same transaction that decrements the ref
> + * count. This avoids duplicate decrements in case the rest of the work
> + * spills over to subsequent transactions.
> + */
> + entry->e_value_inum = 0;
> + entry->e_value_size = 0;
> +
> + dirty = true;
> + }
> +
> + if (dirty) {
> + /*
> + * Note that we are deliberately skipping csum calculation for
> + * the final update because we do not expect any journal
> + * restarts until xattr block is freed.
> + */
> +
> + err = ext4_handle_dirty_metadata(handle, NULL, bh);
> + if (err)
> + ext4_warning_inode(parent,
> + "handle dirty metadata err=%d", err);
> + }
> +}
> +
> /*
> * Release the xattr block BH: If the reference count is > 1, decrement it;
> * otherwise free the block.
> @@ -1985,42 +2110,6 @@ ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
> return 0;
> }
>
> -/**
> - * Add xattr inode to orphan list
> - */
> -static int
> -ext4_xattr_inode_orphan_add(handle_t *handle, struct inode *inode, int credits,
> - struct ext4_xattr_inode_array *ea_inode_array)
> -{
> - int idx = 0, error = 0;
> - struct inode *ea_inode;
> -
> - if (ea_inode_array == NULL)
> - return 0;
> -
> - for (; idx < ea_inode_array->count; ++idx) {
> - if (!ext4_handle_has_enough_credits(handle, credits)) {
> - error = ext4_journal_extend(handle, credits);
> - if (error > 0)
> - error = ext4_journal_restart(handle, credits);
> -
> - if (error != 0) {
> - ext4_warning(inode->i_sb,
> - "couldn't extend journal "
> - "(err %d)", error);
> - return error;
> - }
> - }
> - ea_inode = ea_inode_array->inodes[idx];
> - inode_lock(ea_inode);
> - ext4_orphan_add(handle, ea_inode);
> - inode_unlock(ea_inode);
> - /* the inode's i_count will be released by caller */
> - }
> -
> - return 0;
> -}
> -
> /*
> * ext4_xattr_delete_inode()
> *
> @@ -2033,16 +2122,23 @@ ext4_xattr_inode_orphan_add(handle_t *handle, struct inode *inode, int credits,
> */
> int
> ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
> - struct ext4_xattr_inode_array **ea_inode_array)
> + struct ext4_xattr_inode_array **ea_inode_array,
> + int extra_credits)
> {
> struct buffer_head *bh = NULL;
> struct ext4_xattr_ibody_header *header;
> struct ext4_inode *raw_inode;
> - struct ext4_iloc iloc;
> - struct ext4_xattr_entry *entry;
> - struct inode *ea_inode;
> - unsigned int ea_ino;
> - int credits = 3, error = 0;
> + struct ext4_iloc iloc = { .bh = NULL };
> + int error;
> +
> + error = ext4_xattr_ensure_credits(handle, inode, extra_credits,
> + NULL /* bh */,
> + false /* dirty */,
> + false /* block_csum */);
> + if (error) {
> + EXT4_ERROR_INODE(inode, "ensure credits (error %d)", error);
> + goto cleanup;
> + }
>
> if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
> goto delete_external_ea;
> @@ -2050,31 +2146,20 @@ ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
> error = ext4_get_inode_loc(inode, &iloc);
> if (error)
> goto cleanup;
> +
> + error = ext4_journal_get_write_access(handle, iloc.bh);
> + if (error)
> + goto cleanup;
> +
> raw_inode = ext4_raw_inode(&iloc);
> header = IHDR(inode, raw_inode);
> - for (entry = IFIRST(header); !IS_LAST_ENTRY(entry);
> - entry = EXT4_XATTR_NEXT(entry)) {
> - if (!entry->e_value_inum)
> - continue;
> - ea_ino = le32_to_cpu(entry->e_value_inum);
> - error = ext4_xattr_inode_iget(inode, ea_ino, &ea_inode);
> - if (error)
> - continue;
> - error = ext4_expand_inode_array(ea_inode_array, ea_inode);
> - if (error) {
> - iput(ea_inode);
> - brelse(iloc.bh);
> - goto cleanup;
> - }
> - entry->e_value_inum = 0;
> - }
> - brelse(iloc.bh);
> + ext4_xattr_inode_remove_all(handle, inode, iloc.bh, IFIRST(header),
> + false /* block_csum */, ea_inode_array,
> + extra_credits);
>
> delete_external_ea:
> if (!EXT4_I(inode)->i_file_acl) {
> - /* add xattr inode to orphan list */
> - error = ext4_xattr_inode_orphan_add(handle, inode, credits,
> - *ea_inode_array);
> + error = 0;
> goto cleanup;
> }
> bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
> @@ -2092,46 +2177,32 @@ ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
> goto cleanup;
> }
>
> - for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
> - entry = EXT4_XATTR_NEXT(entry)) {
> - if (!entry->e_value_inum)
> - continue;
> - ea_ino = le32_to_cpu(entry->e_value_inum);
> - error = ext4_xattr_inode_iget(inode, ea_ino, &ea_inode);
> - if (error)
> - continue;
> - error = ext4_expand_inode_array(ea_inode_array, ea_inode);
> - if (error)
> - goto cleanup;
> - entry->e_value_inum = 0;
> - }
> -
> - /* add xattr inode to orphan list */
> - error = ext4_xattr_inode_orphan_add(handle, inode, credits,
> - *ea_inode_array);
> - if (error)
> - goto cleanup;
> -
> - if (!IS_NOQUOTA(inode))
> - credits += 2 * EXT4_QUOTA_DEL_BLOCKS(inode->i_sb);
> -
> - if (!ext4_handle_has_enough_credits(handle, credits)) {
> - error = ext4_journal_extend(handle, credits);
> - if (error > 0)
> - error = ext4_journal_restart(handle, credits);
> + if (ext4_has_feature_ea_inode(inode->i_sb)) {
> + error = ext4_journal_get_write_access(handle, bh);
> if (error) {
> - ext4_warning(inode->i_sb,
> - "couldn't extend journal (err %d)", error);
> + EXT4_ERROR_INODE(inode, "write access %llu",
> + EXT4_I(inode)->i_file_acl);
> goto cleanup;
> }
> + ext4_xattr_inode_remove_all(handle, inode, bh,
> + BFIRST(bh),
> + true /* block_csum */,
> + ea_inode_array,
> + extra_credits);
> }
>
> ext4_xattr_release_block(handle, inode, bh);
> + /* Update i_file_acl within the same transaction that releases block. */
> EXT4_I(inode)->i_file_acl = 0;
> -
> + error = ext4_mark_inode_dirty(handle, inode);
> + if (error) {
> + EXT4_ERROR_INODE(inode, "mark inode dirty (error %d)",
> + error);
> + goto cleanup;
> + }
> cleanup:
> + brelse(iloc.bh);
> brelse(bh);
> -
> return error;
> }
>
> diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
> index adf761518a73..b2005a2716d9 100644
> --- a/fs/ext4/xattr.h
> +++ b/fs/ext4/xattr.h
> @@ -169,7 +169,8 @@ extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len);
>
> extern int ext4_xattr_inode_unlink(struct inode *inode, unsigned long ea_ino);
> extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
> - struct ext4_xattr_inode_array **array);
> + struct ext4_xattr_inode_array **array,
> + int extra_credits);
> extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array);
>
> extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
> --
> 2.13.1.508.gb3defc5cc-goog
>
Cheers, Andreas
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