drivers/quota.makeBackingFsDev(): use mknod+rename #1280
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Use mknod() followed by rename() to create the "backingFsBlockDev" device, instead of unlink() followed by mknod(), to remove the window where the node won't exist if we're just going to end up replacing it with an identical device node. Signed-off-by: Nalin Dahyabhai <[email protected]>
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May be applicable to https://bugzilla.redhat.com/show_bug.cgi?id=2091214, but without knowing what removed /var/lib/containers/storage/overlay/backingFsBlockDev, we can't be sure. |
rhatdan
reviewed
Jul 7, 2022
| if err := unix.Mknod(backingFsBlockDevTmp, unix.S_IFBLK|0600, int(stat.Dev)); err != nil { | ||
| return "", fmt.Errorf("Failed to mknod %s: %v", backingFsBlockDevTmp, err) | ||
| } | ||
| if err := unix.Rename(backingFsBlockDevTmp, backingFsBlockDev); err != nil { |
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Rename is allowed over an existing device?
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Per rename(2), yes. We'll get EEXIST back if we're using renameat2() and with a RENAME_NOREPLACE flag.
rhatdan
approved these changes
Jul 7, 2022
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LGTM |
| if err := unix.Mknod(backingFsBlockDev, unix.S_IFBLK|0600, int(stat.Dev)); err != nil { | ||
| return "", fmt.Errorf("Failed to mknod %s: %v", backingFsBlockDev, err) | ||
| if err := unix.Mknod(backingFsBlockDevTmp, unix.S_IFBLK|0600, int(stat.Dev)); err != nil { | ||
| return "", fmt.Errorf("Failed to mknod %s: %v", backingFsBlockDevTmp, err) |
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Suggested change
| return "", fmt.Errorf("Failed to mknod %s: %v", backingFsBlockDevTmp, err) | |
| return "", fmt.Errorf("failed to mknod %s: %w", backingFsBlockDevTmp, err) |
| return "", fmt.Errorf("Failed to mknod %s: %v", backingFsBlockDevTmp, err) | ||
| } | ||
| if err := unix.Rename(backingFsBlockDevTmp, backingFsBlockDev); err != nil { | ||
| return "", fmt.Errorf("Failed to rename %s to %s: %v", backingFsBlockDevTmp, backingFsBlockDev, err) |
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Suggested change
| return "", fmt.Errorf("Failed to rename %s to %s: %v", backingFsBlockDevTmp, backingFsBlockDev, err) | |
| return "", fmt.Errorf("failed to rename %s to %s: %w", backingFsBlockDevTmp, backingFsBlockDev, err) |
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Use mknod() followed by rename() to create the "backingFsBlockDev" device, instead of unlink() followed by mknod(), to remove the window where the node won't exist if we're just going to end up replacing it with an identical device node.