libxfs: remove never-read "offset" assignment in readbufr_map & writebufr
PATCH 1/1 libxfs: remove never-read "offset" assignment in readbufr_map & writebufr
libxfs_readbufr_map() & libxfs_writebufr() iterate over bp->b_map[] and read each chunk. The loops start out correctly, getting the offset from bm_bn and the length from bm_len. After the IO it correctly advances the target buffer pointer by len, but then inexplicably advances "offset" by len as well. The whole point of this exercise is to handle discontiguous ranges - marching offset along by length of IO done is incorrect.
Thankfully offset is immediately reset to the proper value again at the top of the loop for the next range, so this is harmless, other than being confusing.
---
libxfs/rdwr.c +0 -2
@@ -758,7 +758,6 @@ libxfs_readbufr_map(struct xfs_buftarg *btp, struct xfs_buf *bp, int flags)break ; } buf += len; - offset += len; }if (!error)
@@ -878,7 +877,6 @@ libxfs_writebufr(xfs_buf_t *bp)break ; } buf += len; - offset += len; } }
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Quoted 10 lines · Eric Sandeen
libxfs_readbufr_map()&
libxfs_writebufr()iterate over bp->b_map[] and read each chunk. The loops start out correctly, getting the offset frombm_bnand the length frombm_len. After the IO it correctly advances the target buffer pointer by len, but then inexplicably advances "offset" by len as well. The whole point of this exercise is to handle discontiguous ranges - marching offset along by length of IO done is incorrect.
Quoted 5 lines
Thankfully offset is immediately reset to the proper value again at the top of the loop for the next range, so this is harmless, other than being confusing.
Signed-off-by Eric Sandeen<[email protected]>
Looks good.
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