From: Chandan Babu R chandanrlinux@gmail.com
mainline inclusion from mainline-v5.12-rc1 commit 02092a2f034fdeabab524ae39c2de86ba9ffa15a category: bugfix bugzilla: 187510,https://gitee.com/openeuler/kernel/issues/I4KIAO
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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A rename operation is essentially a directory entry remove operation from the perspective of parent directory (i.e. src_dp) of rename's source. Hence the only place where we check for extent count overflow for src_dp is in xfs_bmap_del_extent_real(). xfs_bmap_del_extent_real() returns -ENOSPC when it detects a possible extent count overflow and in response, the higher layers of directory handling code do the following: 1. Data/Free blocks: XFS lets these blocks linger until a future remove operation removes them. 2. Dabtree blocks: XFS swaps the blocks with the last block in the Leaf space and unmaps the last block.
For target_dp, there are two cases depending on whether the destination directory entry exists or not.
When destination directory entry does not exist (i.e. target_ip == NULL), extent count overflow check is performed only when transaction has a non-zero sized space reservation associated with it. With a zero-sized space reservation, XFS allows a rename operation to continue only when the directory has sufficient free space in its data/leaf/free space blocks to hold the new entry.
When destination directory entry exists (i.e. target_ip != NULL), all we need to do is change the inode number associated with the already existing entry. Hence there is no need to perform an extent count overflow check.
Signed-off-by: Chandan Babu R chandanrlinux@gmail.com Reviewed-by: Darrick J. Wong darrick.wong@oracle.com Signed-off-by: Darrick J. Wong darrick.wong@oracle.com Signed-off-by: Yu Kuai yukuai3@huawei.com Signed-off-by: Guo Xuenan guoxuenan@huawei.com Reviewed-by: Zhang Yi yi.zhang@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- fs/xfs/libxfs/xfs_bmap.c | 3 +++ fs/xfs/xfs_inode.c | 44 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 89ccf059d1aa..97dbb8af9fa0 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -5148,6 +5148,9 @@ xfs_bmap_del_extent_real( * until a future remove operation. Dabtree blocks would be * swapped with the last block in the leaf space and then the * new last block will be unmapped. + * + * The above logic also applies to the source directory entry of + * a rename operation. */ error = xfs_iext_count_may_overflow(ip, whichfork, 1); if (error) { diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index 31c1f8f951a0..c9cf34a4fee8 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -3310,6 +3310,35 @@ xfs_rename( /* * Check for expected errors before we dirty the transaction * so we can return an error without a transaction abort. + * + * Extent count overflow check: + * + * From the perspective of src_dp, a rename operation is essentially a + * directory entry remove operation. Hence the only place where we check + * for extent count overflow for src_dp is in + * xfs_bmap_del_extent_real(). xfs_bmap_del_extent_real() returns + * -ENOSPC when it detects a possible extent count overflow and in + * response, the higher layers of directory handling code do the + * following: + * 1. Data/Free blocks: XFS lets these blocks linger until a + * future remove operation removes them. + * 2. Dabtree blocks: XFS swaps the blocks with the last block in the + * Leaf space and unmaps the last block. + * + * For target_dp, there are two cases depending on whether the + * destination directory entry exists or not. + * + * When destination directory entry does not exist (i.e. target_ip == + * NULL), extent count overflow check is performed only when transaction + * has a non-zero sized space reservation associated with it. With a + * zero-sized space reservation, XFS allows a rename operation to + * continue only when the directory has sufficient free space in its + * data/leaf/free space blocks to hold the new entry. + * + * When destination directory entry exists (i.e. target_ip != NULL), all + * we need to do is change the inode number associated with the already + * existing entry. Hence there is no need to perform an extent count + * overflow check. */ if (target_ip == NULL) { /* @@ -3320,6 +3349,12 @@ xfs_rename( error = xfs_dir_canenter(tp, target_dp, target_name); if (error) goto out_trans_cancel; + } else { + error = xfs_iext_count_may_overflow(target_dp, + XFS_DATA_FORK, + XFS_IEXT_DIR_MANIP_CNT(mp)); + if (error) + goto out_trans_cancel; } } else { /* @@ -3485,9 +3520,16 @@ xfs_rename( if (wip) { error = xfs_dir_replace(tp, src_dp, src_name, wip->i_ino, spaceres); - } else + } else { + /* + * NOTE: We don't need to check for extent count overflow here + * because the dir remove name code will leave the dir block in + * place if the extent count would overflow. + */ error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino, spaceres); + } + if (error) goto out_trans_cancel;