Andreas Dilger wrote: > On Nov 14, 2006 09:25 -0600, Eric Sandeen wrote: >> has an image with a corrupt directory inode - despite having only 4 blocks, >> it has an extremely large i_size. >> >> It seems odd to me that readdir bails out with an error on the first bad >> page, while lookup keeps trying. Shouldn't these be consistent? And if >> so, which is the desired behavior? > > I'd prefer that readdir _should_ return all of the valid directory blocks > it can find. Otherwise, it makes on average 1/2 of the files in that dir > inaccessible. in the very rare case of corruption, yes... although if ext2 is mounted with anything other than errors=continue the fs is going to turn somewhat useless shortly thereafter anyway. >> Or, perhaps a check high up that says if i_size doesn't correlate to >> i_blocks, this inode is corrupt, and bail out early. > > We did that for ext3, no? Yes, this is similar. In that case we kept trying bad pages until we had exceeded the block count, IIRC. I was considering the possibility of checking blocks vs. size right at the top (ext3_readdir or lookup) and if they don't correspond, don't even bother because the information we're starting with is known to be bad. Looking at this one I wonder if the ext3 fix was too specific/targeted - I'll double check it. > It would make sense to fix ext2 in the same way. > I'd suggest bailing out "early" == min(i_size >> blocksize, i_blocks). > The i_blocks count is an upper limit, because it includes the overhead of > indirect blocks. Directories cannot be sparse. so we could either a) keep processing pages based on i_size, until we have passed i_blocks, or b) if i_size & i_blocks don't match, immediately bail out because we know we have found a corrupted inode (vs. a "normal" unreadable block...) -Eric - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
