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Anton Altaparmakov wrote: > On Mon, 2005-10-10 at 18:07 -0700, Andrew Morton wrote: > >>Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> wrote: >> >>> On Mon, 10 Oct 2005, Andrew Morton wrote: >>> >>> > Anton Altaparmakov <aia21@cam.ac.uk> wrote: >>> >> >>> >> > Maybe the best solution is neither one nor another. Testing and failing >>> >> > gracefully seems better. >>> >> > >>> >> > What do you think? >>> >> >>> >> I certainly agree with you there. I neither want a deadlock nor >>> >> corruption. (-: >>> > >>> > Yup. In the present implementation __getblk_slow() "cannot fail". It's >>> > conceivable that at some future stage we'll change __getblk_slow() so that >>> > it returns NULL on an out-of-memory condition. >>> >>> The question is if it is desired --- it will make bread return NULL on >>> out-of-memory condition, callers will treat it like an IO error, skipping >>> access to the affected block, causing damage on perfectly healthy >>> filesystem. >> >>Yes, that is a bit dumb. A filesystem might indeed want to take different >>action for ENOMEM versus EIO. >> >> >>> I liked what linux-2.0 did in this case --- if the kernel was out of >>> memory, getblk just took another buffer, wrote it if it was dirty and used >>> it. Except for writeable loopback device (where writing one buffer >>> generates more dirty buffers), it couldn't deadlock. >> >>Wouldn't it be better if bread() were to return ERR_PTR(-EIO) or >>ERR_PTR(-ENOMEM)? Big change. > > > It would indeed. Much better. And whilst at it, it would be even > better if we had a lot more error codes like "ERR_PTR(-EDEVUNPLUGGED)" > for example... But that would be an even better change. Anyone feeling > like touching every block driver in the kernel? (-; > I have actually done this http://marc.theaimsgroup.com/?l=linux-scsi&m=112487427230642&w=2 (this is just the bio users, the end_that_request_first/chunk users are in another patch). I am just trying to figure out how to support some wierd scsi HW before reposting. If you have suggestions about how to implement the bitmap suggestion in that thread I am listening too (I implemented it like scsi's scsi_cmnd result field). - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | |||||||||
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