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ext4: support large block size in ext4_readdir() 

In ext4_readdir(), page_cache_sync_readahead() is used to readahead mapped
physical blocks. With LBS support, this can lead to a negative right shift.

To fix this, the page index is now calculated by first converting the
physical block number (pblk) to a file position (pos) before converting
it to a page index. Also, the correct number of pages to readahead is now
passed.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Message-ID: <20251121090654.631996-9-libaokun@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Baokun Li 2025-11-21 17:06:38 +08:00 committed by Theodore Ts'o
parent 6a28b5c990
commit 609c5e0081
1 changed files with 4 additions and 4 deletions
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8
fs/ext4/dir.c
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@ -192,13 +192,13 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
continue; continue;
} }
if (err > 0) { if (err > 0) {
pgoff_t index = map.m_pblk >> pgoff_t index = map.m_pblk << inode->i_blkbits >>
(PAGE_SHIFT - inode->i_blkbits); PAGE_SHIFT;
if (!ra_has_index(&file->f_ra, index)) if (!ra_has_index(&file->f_ra, index))
page_cache_sync_readahead( page_cache_sync_readahead(
sb->s_bdev->bd_mapping, sb->s_bdev->bd_mapping,
&file->f_ra, file, &file->f_ra, file, index,
index, 1); 1 << EXT4_SB(sb)->s_min_folio_order);
file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT; file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
bh = ext4_bread(NULL, inode, map.m_lblk, 0); bh = ext4_bread(NULL, inode, map.m_lblk, 0);
if (IS_ERR(bh)) { if (IS_ERR(bh)) {