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由 Eric Whitney 提交于
Ext4 may not free clusters correctly when punching holes in bigalloc file systems under high load conditions. If it's not possible to extend and restart the journal in ext4_ext_rm_leaf() when preparing to remove blocks from a punched region, a retry of the entire punch operation is triggered in ext4_ext_remove_space(). This causes a partial cluster to be set to the first cluster in the extent found to the right of the punched region. However, if the punch operation prior to the retry had made enough progress to delete one or more extents and a partial cluster candidate for freeing had already been recorded, the retry would overwrite the partial cluster. The loss of this information makes it impossible to correctly free the original partial cluster in all cases. This bug can cause generic/476 to fail when run as part of xfstests-bld's bigalloc and bigalloc_1k test cases. The failure is reported when e2fsck detects bad iblocks counts greater than expected in units of whole clusters and also detects a number of negative block bitmap differences equal to the iblocks discrepancy in cluster units. Signed-off-by: NEric Whitney <enwlinux@gmail.com> Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
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