diff options
Diffstat (limited to 'sys/kern/vfs_vnops.c')
| -rw-r--r-- | sys/kern/vfs_vnops.c | 100 |
1 files changed, 16 insertions, 84 deletions
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c index 18a9ac3..f07df31 100644 --- a/sys/kern/vfs_vnops.c +++ b/sys/kern/vfs_vnops.c @@ -770,10 +770,9 @@ vn_read(fp, uio, active_cred, flags, td) struct thread *td; { struct vnode *vp; - struct mtx *mtxp; + off_t orig_offset; int error, ioflag; int advice; - off_t offset, start, end; KASSERT(uio->uio_td == td, ("uio_td %p is not td %p", uio->uio_td, td)); @@ -797,7 +796,7 @@ vn_read(fp, uio, active_cred, flags, td) /* Disable read-ahead for random I/O. */ break; } - offset = uio->uio_offset; + orig_offset = uio->uio_offset; #ifdef MAC error = mac_vnode_check_read(active_cred, fp->f_cred, vp); @@ -807,39 +806,14 @@ vn_read(fp, uio, active_cred, flags, td) fp->f_nextoff = uio->uio_offset; VOP_UNLOCK(vp, 0); if (error == 0 && advice == POSIX_FADV_NOREUSE && - offset != uio->uio_offset) { + orig_offset != uio->uio_offset) /* - * Use POSIX_FADV_DONTNEED to flush clean pages and - * buffers for the backing file after a - * POSIX_FADV_NOREUSE read(2). To optimize the common - * case of using POSIX_FADV_NOREUSE with sequential - * access, track the previous implicit DONTNEED - * request and grow this request to include the - * current read(2) in addition to the previous - * DONTNEED. With purely sequential access this will - * cause the DONTNEED requests to continously grow to - * cover all of the previously read regions of the - * file. This allows filesystem blocks that are - * accessed by multiple calls to read(2) to be flushed - * once the last read(2) finishes. + * Use POSIX_FADV_DONTNEED to flush pages and buffers + * for the backing file after a POSIX_FADV_NOREUSE + * read(2). */ - start = offset; - end = uio->uio_offset - 1; - mtxp = mtx_pool_find(mtxpool_sleep, fp); - mtx_lock(mtxp); - if (fp->f_advice != NULL && - fp->f_advice->fa_advice == POSIX_FADV_NOREUSE) { - if (start != 0 && fp->f_advice->fa_prevend + 1 == start) - start = fp->f_advice->fa_prevstart; - else if (fp->f_advice->fa_prevstart != 0 && - fp->f_advice->fa_prevstart == end + 1) - end = fp->f_advice->fa_prevend; - fp->f_advice->fa_prevstart = start; - fp->f_advice->fa_prevend = end; - } - mtx_unlock(mtxp); - error = VOP_ADVISE(vp, start, end, POSIX_FADV_DONTNEED); - } + error = VOP_ADVISE(vp, orig_offset, uio->uio_offset - 1, + POSIX_FADV_DONTNEED); return (error); } @@ -856,10 +830,9 @@ vn_write(fp, uio, active_cred, flags, td) { struct vnode *vp; struct mount *mp; - struct mtx *mtxp; + off_t orig_offset; int error, ioflag, lock_flags; int advice; - off_t offset, start, end; KASSERT(uio->uio_td == td, ("uio_td %p is not td %p", uio->uio_td, td)); @@ -902,7 +875,7 @@ vn_write(fp, uio, active_cred, flags, td) /* XXX: Is this correct? */ break; } - offset = uio->uio_offset; + orig_offset = uio->uio_offset; #ifdef MAC error = mac_vnode_check_write(active_cred, fp->f_cred, vp); @@ -914,55 +887,14 @@ vn_write(fp, uio, active_cred, flags, td) if (vp->v_type != VCHR) vn_finished_write(mp); if (error == 0 && advice == POSIX_FADV_NOREUSE && - offset != uio->uio_offset) { + orig_offset != uio->uio_offset) /* - * Use POSIX_FADV_DONTNEED to flush clean pages and - * buffers for the backing file after a - * POSIX_FADV_NOREUSE write(2). To optimize the - * common case of using POSIX_FADV_NOREUSE with - * sequential access, track the previous implicit - * DONTNEED request and grow this request to include - * the current write(2) in addition to the previous - * DONTNEED. With purely sequential access this will - * cause the DONTNEED requests to continously grow to - * cover all of the previously written regions of the - * file. - * - * Note that the blocks just written are almost - * certainly still dirty, so this only works when - * VOP_ADVISE() calls from subsequent writes push out - * the data written by this write(2) once the backing - * buffers are clean. However, as compared to forcing - * IO_DIRECT, this gives much saner behavior. Write - * clustering is still allowed, and clean pages are - * merely moved to the cache page queue rather than - * outright thrown away. This means a subsequent - * read(2) can still avoid hitting the disk if the - * pages have not been reclaimed. - * - * This does make POSIX_FADV_NOREUSE largely useless - * with non-sequential access. However, sequential - * access is the more common use case and the flag is - * merely advisory. + * Use POSIX_FADV_DONTNEED to flush pages and buffers + * for the backing file after a POSIX_FADV_NOREUSE + * write(2). */ - start = offset; - end = uio->uio_offset - 1; - mtxp = mtx_pool_find(mtxpool_sleep, fp); - mtx_lock(mtxp); - if (fp->f_advice != NULL && - fp->f_advice->fa_advice == POSIX_FADV_NOREUSE) { - if (start != 0 && fp->f_advice->fa_prevend + 1 == start) - start = fp->f_advice->fa_prevstart; - else if (fp->f_advice->fa_prevstart != 0 && - fp->f_advice->fa_prevstart == end + 1) - end = fp->f_advice->fa_prevend; - fp->f_advice->fa_prevstart = start; - fp->f_advice->fa_prevend = end; - } - mtx_unlock(mtxp); - error = VOP_ADVISE(vp, start, end, POSIX_FADV_DONTNEED); - } - + error = VOP_ADVISE(vp, orig_offset, uio->uio_offset - 1, + POSIX_FADV_DONTNEED); unlock: return (error); } |
