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Message-ID: <Z2KhaFhqwQMy2Fk/@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com>
Date: Wed, 18 Dec 2024 15:48:16 +0530
From: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
To: Zhang Yi <yi.zhang@...weicloud.com>
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca,
jack@...e.cz, yi.zhang@...wei.com, chengzhihao1@...wei.com,
yukuai3@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH v4 06/10] ext4: refactor ext4_collapse_range()
On Mon, Dec 16, 2024 at 09:39:11AM +0800, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@...wei.com>
>
> Simplify ext4_collapse_range() and align its code style with that of
> ext4_zero_range() and ext4_punch_hole(). Refactor it by: a) renaming
> variables, b) removing redundant input parameter checks and moving
> the remaining checks under i_rwsem in preparation for future
> refactoring, and c) renaming the three stale error tags.
Looks good, feel free to add:
Reviewed-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
>
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
> Reviewed-by: Jan Kara <jack@...e.cz>
> ---
> fs/ext4/extents.c | 103 +++++++++++++++++++++-------------------------
> 1 file changed, 48 insertions(+), 55 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 97ad6fea58d3..8a0a720803a8 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -5292,43 +5292,36 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
> struct inode *inode = file_inode(file);
> struct super_block *sb = inode->i_sb;
> struct address_space *mapping = inode->i_mapping;
> - ext4_lblk_t punch_start, punch_stop;
> + loff_t end = offset + len;
> + ext4_lblk_t start_lblk, end_lblk;
> handle_t *handle;
> unsigned int credits;
> - loff_t new_size, ioffset;
> + loff_t start, new_size;
> int ret;
>
> - /*
> - * We need to test this early because xfstests assumes that a
> - * collapse range of (0, 1) will return EOPNOTSUPP if the file
> - * system does not support collapse range.
> - */
> - if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
> - return -EOPNOTSUPP;
> + trace_ext4_collapse_range(inode, offset, len);
>
> - /* Collapse range works only on fs cluster size aligned regions. */
> - if (!IS_ALIGNED(offset | len, EXT4_CLUSTER_SIZE(sb)))
> - return -EINVAL;
> + inode_lock(inode);
>
> - trace_ext4_collapse_range(inode, offset, len);
> + /* Currently just for extent based files */
> + if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
> + ret = -EOPNOTSUPP;
> + goto out;
> + }
>
> - punch_start = offset >> EXT4_BLOCK_SIZE_BITS(sb);
> - punch_stop = (offset + len) >> EXT4_BLOCK_SIZE_BITS(sb);
> + /* Collapse range works only on fs cluster size aligned regions. */
> + if (!IS_ALIGNED(offset | len, EXT4_CLUSTER_SIZE(sb))) {
> + ret = -EINVAL;
> + goto out;
> + }
>
> - inode_lock(inode);
> /*
> * There is no need to overlap collapse range with EOF, in which case
> * it is effectively a truncate operation
> */
> - if (offset + len >= inode->i_size) {
> + if (end >= inode->i_size) {
> ret = -EINVAL;
> - goto out_mutex;
> - }
> -
> - /* Currently just for extent based files */
> - if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
> - ret = -EOPNOTSUPP;
> - goto out_mutex;
> + goto out;
> }
>
> /* Wait for existing dio to complete */
> @@ -5336,7 +5329,7 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
>
> ret = file_modified(file);
> if (ret)
> - goto out_mutex;
> + goto out;
>
> /*
> * Prevent page faults from reinstantiating pages we have released from
> @@ -5346,55 +5339,52 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
>
> ret = ext4_break_layouts(inode);
> if (ret)
> - goto out_mmap;
> + goto out_invalidate_lock;
>
> /*
> + * Write tail of the last page before removed range and data that
> + * will be shifted since they will get removed from the page cache
> + * below. We are also protected from pages becoming dirty by
> + * i_rwsem and invalidate_lock.
> * Need to round down offset to be aligned with page size boundary
> * for page size > block size.
> */
> - ioffset = round_down(offset, PAGE_SIZE);
> - /*
> - * Write tail of the last page before removed range since it will get
> - * removed from the page cache below.
> - */
> - ret = filemap_write_and_wait_range(mapping, ioffset, offset);
> - if (ret)
> - goto out_mmap;
> - /*
> - * Write data that will be shifted to preserve them when discarding
> - * page cache below. We are also protected from pages becoming dirty
> - * by i_rwsem and invalidate_lock.
> - */
> - ret = filemap_write_and_wait_range(mapping, offset + len,
> - LLONG_MAX);
> + start = round_down(offset, PAGE_SIZE);
> + ret = filemap_write_and_wait_range(mapping, start, offset);
> + if (!ret)
> + ret = filemap_write_and_wait_range(mapping, end, LLONG_MAX);
> if (ret)
> - goto out_mmap;
> - truncate_pagecache(inode, ioffset);
> + goto out_invalidate_lock;
> +
> + truncate_pagecache(inode, start);
>
> credits = ext4_writepage_trans_blocks(inode);
> handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
> if (IS_ERR(handle)) {
> ret = PTR_ERR(handle);
> - goto out_mmap;
> + goto out_invalidate_lock;
> }
> ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_FALLOC_RANGE, handle);
>
> + start_lblk = offset >> inode->i_blkbits;
> + end_lblk = (offset + len) >> inode->i_blkbits;
> +
> down_write(&EXT4_I(inode)->i_data_sem);
> ext4_discard_preallocations(inode);
> - ext4_es_remove_extent(inode, punch_start, EXT_MAX_BLOCKS - punch_start);
> + ext4_es_remove_extent(inode, start_lblk, EXT_MAX_BLOCKS - start_lblk);
>
> - ret = ext4_ext_remove_space(inode, punch_start, punch_stop - 1);
> + ret = ext4_ext_remove_space(inode, start_lblk, end_lblk - 1);
> if (ret) {
> up_write(&EXT4_I(inode)->i_data_sem);
> - goto out_stop;
> + goto out_handle;
> }
> ext4_discard_preallocations(inode);
>
> - ret = ext4_ext_shift_extents(inode, handle, punch_stop,
> - punch_stop - punch_start, SHIFT_LEFT);
> + ret = ext4_ext_shift_extents(inode, handle, end_lblk,
> + end_lblk - start_lblk, SHIFT_LEFT);
> if (ret) {
> up_write(&EXT4_I(inode)->i_data_sem);
> - goto out_stop;
> + goto out_handle;
> }
>
> new_size = inode->i_size - len;
> @@ -5402,16 +5392,19 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
> EXT4_I(inode)->i_disksize = new_size;
>
> up_write(&EXT4_I(inode)->i_data_sem);
> - if (IS_SYNC(inode))
> - ext4_handle_sync(handle);
> ret = ext4_mark_inode_dirty(handle, inode);
> + if (ret)
> + goto out_handle;
> +
> ext4_update_inode_fsync_trans(handle, inode, 1);
> + if (IS_SYNC(inode))
> + ext4_handle_sync(handle);
>
> -out_stop:
> +out_handle:
> ext4_journal_stop(handle);
> -out_mmap:
> +out_invalidate_lock:
> filemap_invalidate_unlock(mapping);
> -out_mutex:
> +out:
> inode_unlock(inode);
> return ret;
> }
> --
> 2.46.1
>
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