On Thu, 2008-03-13 at 11:06 +1300, Charles Manning wrote: > I'm trying to figure out a reasonable approach to implementing xattr in YAFFS. > > >From my (limited) knowledge of xattr it seems that in theory you could store a > multi-Mbyte database in xattr, but in practice a smaller size is far more > reasonable. Clearly storing/managing a small blob is going to be a lot > simpler. > > What is the cut off of a reasonable xattr blob size? 1kbytes? 2kbytes?... > > Thanx. > > Charles > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html I don't know about specific file system limits on xattrs but from a user-space perspective the sys_setxattr->setxattr call chain enforces a limit of no more than 64k on an xattr value. In addition the list of xattr names is also limited to 64k with a name being no longer than 255 chars. From your wording above it seems that you want to store the xattrs as their own records. One approach (which is different from what I think you want) is to store the xattrs in the inode upto a point and then if necessary allocate space from them elsewhere. I'm not familiar with what you are trying to implement but I believe this is the way XFS handles xattrs. #define XATTR_NAME_MAX 255 /* # chars in an extended attribute name */ #define XATTR_SIZE_MAX 65536 /* size of an extended attribute value (64k) */ #define XATTR_LIST_MAX 65536 /* size of extended attribute namelist (64k) */ Dave -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
