I have discovered a bug which causes e2fsck to return with a "Attempt to
read block from filesystem resulted in short read..." when checking
certain partitions. First my pertinent setup:
/dev/hda 20 GB WD drive
/dev/hdb 6 GB Quantum drive
/dev/hdc 13 GB Maxtor drive with geometry [1653/255/63] (3 partitions)
/dev/hdd LS-120
Since kernel 2.3.40, I have been getting "short read" errors when
attempting to e2fsck /dev/hdc2 and /dev/hdc3. I traced the problem to
fs/partitions/check.c. In the function grok_partitions, if the size input
argument is 0, the blk_size[dev->major] is set to NULL, and never
updated.
When the LS-120 (/dev/hdd) is processed in this function, since
there is no disk in the drive, the size argument is 0, and the
blk_size[dev->major] is set to NULL. This erases the previous pointer
which contained the partition information for /dev/hdc! The fix I'm
using is below, but I don't know if it's the correct way to fix the
problem.
diff -U 3 ./check.c /usr/src/linux/fs/partitions/check.c
--- ./check.c Sun Feb 20 15:21:29 2000
+++ /usr/src/linux/fs/partitions/check.c Mon Feb 21 02:19:25 2000
@@ -396,11 +396,16 @@
int first_minor = drive << dev->minor_shift;
int end_minor = first_minor + dev->max_p;
- blk_size[dev->major] = NULL;
+ if(!dev->sizes)
+ blk_size[dev->major] = NULL;
+
dev->part[first_minor].nr_sects = size;
/* No Such Agen^Wdevice or no minors to use for partitions */
if (!size || minors == 1)
return;
+
+ blk_size[dev->major] = NULL;
+
check_partition(dev, MKDEV(dev->major, first_minor), 1 + first_minor);
/*
cut--------------------------------------------------------------------------
The first block to report a short read error on /dev/hdc3 was 2492572, and
the next was 2623358. Why with the blk_size[dev->major] (for major 22)
set to NULL, didn't I get "short read" errors for every block? Or on the
other hand, why did I get "short read" errors at all?
V/R
Michael Pakovic
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