On Sun 21-05-17 15:59:39, Eryu Guan wrote: > xfs_find_get_desired_pgoff() is used to search for offset of hole or > data in page range [index, end] (both inclusive), and the max number > of pages to search should be at least one, if end == index. > Otherwise the only page is missed and no hole or data is found, > which is not correct. > > When block size is smaller than page size, this can be demonstrated > by preallocating a file with size smaller than page size and writing > data to the last block. E.g. run this xfs_io command on a 1k block > size XFS on x86_64 host. > > # xfs_io -fc "falloc 0 3k" -c "pwrite 2k 1k" \ > -c "seek -d 0" /mnt/xfs/testfile > wrote 1024/1024 bytes at offset 2048 > 1 KiB, 1 ops; 0.0000 sec (33.675 MiB/sec and 34482.7586 ops/sec) > Whence Result > DATA EOF > > Data at offset 2k was missed, and lseek(2) returned ENXIO. > > This is unconvered by generic/285 subtest 07 and 08 on ppc64 host, > where pagesize is 64k. Because a recent change to generic/285 > reduced the preallocated file size to smaller than 64k. > > Cc: stable@xxxxxxxxxxxxxxx # v3.7+ > Signed-off-by: Eryu Guan <eguan@xxxxxxxxxx> Looks good. You can add: Reviewed-by: Jan Kara <jack@xxxxxxx> BTW, this was actually introduced by my recent SEEK_HOLE fixes so Darrick, please put this in one batch with them. Thanks! Honza > --- > fs/xfs/xfs_file.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 35703a8..aefa213 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -1049,7 +1049,7 @@ xfs_find_get_desired_pgoff( > unsigned nr_pages; > unsigned int i; > > - want = min_t(pgoff_t, end - index, PAGEVEC_SIZE); > + want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1; > nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index, > want); > /* > -- > 2.9.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
