Disk drive correcting track address during a write operation

1. A disk drive comprising:

(a) a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors and each servo sector comprises a track address identifying the servo track;

(b) a head actuated over the disk; and

(c) control circuitry operable to execute a write operation by:

processing a read signal from the head representing a first track address in one of the servo sectors in order to generate a detected track address;

comparing the detected track address to a first target track address to obtain a first track address error;

generating a correction metric representing a likelihood that the first track address error was caused by a detection error;

if the correction metric exceeds a threshold, correcting the detected track address in response to the first track address error and continuing with the write operation; and

if the correction metric does not exceed the threshold, aborting the write operation.

2. The disk drive recited in claim 1 , wherein:

(a) the control circuitry comprises a read channel operable to generate the detected track address;

(b) the read channel is further operable to generate a reliability metric for each bit in the detected track address; and

(c) the correction metric is based at least partially on at least one of the reliability metrics.

3. The disk drive recited in claim 2 , wherein the read channel comprises a sequence detector operable to generate the detected track address and the reliability metrics.

4. The disk drive recited in claim 2 , wherein the read channel comprises a slicer operable to generate the detected track address and the reliability metrics.

5. The disk drive recited in claim 1 , wherein:

(a) the read channel comprises a sequence detector operable to generate the detected track address;

(b) the sequence detector comprises a plurality of error events; and

(c) the correction metric is based at least partially on the plurality of error events.

6. The disk drive recited in claim 5 , wherein:

(a) the sequence detector comprises a plurality of error event filters for detecting potential error events in response to read signal sample values and expected sample values; and

(b) the correction metric is based at least partially on the error event filters.

7. The disk drive recited in claim 1 , wherein the control circuitry is further operable to compare the detected track address to a second target track address to obtain a second track address error.

8. The disk drive recited in claim 7 , wherein the control circuitry is further operable to:

(a) select between the first and second track address errors based on the number of error bits in each of the track address errors; and

(b) correct the detected track address in response to the selected track address error if the correction metric exceeds the threshold.

9. The disk drive recited in claim 1 , wherein the control circuitry is further operable to abort the write operation if the number of error bits in the first track address error exceeds an error threshold.

10. A method of performing a write operation in a disk drive, the disk drive comprising a disk having a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors and each servo sector comprises a track address identifying the servo track, and a head actuated over the disk, the method comprising:

processing a read signal from the head representing a first track address in one of the servo sectors in order to generate a detected track address;

comparing the detected track address to a first target track address to obtain a first track address error;

generating a correction metric representing a likelihood that the first track address error was caused by a detection error;

if the correction metric exceeds a threshold, correcting the detected track address in response to the first track address error and continuing with the write operation; and

if the correction metric does not exceed the threshold, aborting the write operation.

11. The method recited in claim 10 , wherein generating the correction metric comprises generating a reliability metric for each bit in the detected track address.

12. The method recited in claim 11 , wherein a sequence detector generates the detected track address and the reliability metrics.

13. The method recited in claim 11 , wherein a slicer generates the detected track address and the reliability metrics.

14. The method recited in claim 10 , wherein the correction metric is generated in response to a plurality of error events of a sequence detector.

15. The method recited in claim 14 , wherein the correction metric is generated in response to a plurality of error event filters for detecting potential error events in response to read signal sample values and expected sample values.

16. The method recited in claim 10 , further comprising comparing the detected track address to a second target track address to obtain a second track address error.

17. The method recited in claim 16 , further comprising:

selecting between the first and second track address errors based on the number of error bits in each of the track address errors; and

correcting the detected track address in response to the selected track address error if the correction metric exceeds the threshold.

18. The method recited in claim 10 , further comprising aborting the write operation if the number of error bits in the first track address error exceeds an error threshold.