diff options
Diffstat (limited to 'fs/direct-io.c')
-rw-r--r-- | fs/direct-io.c | 74 |
1 files changed, 20 insertions, 54 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index a10cb91cadea..51f270b479b6 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c | |||
@@ -1136,8 +1136,27 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, | |||
1136 | return ret; | 1136 | return ret; |
1137 | } | 1137 | } |
1138 | 1138 | ||
1139 | /* | ||
1140 | * This is a library function for use by filesystem drivers. | ||
1141 | * | ||
1142 | * The locking rules are governed by the flags parameter: | ||
1143 | * - if the flags value contains DIO_LOCKING we use a fancy locking | ||
1144 | * scheme for dumb filesystems. | ||
1145 | * For writes this function is called under i_mutex and returns with | ||
1146 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | ||
1147 | * taken and dropped again before returning. | ||
1148 | * For reads and writes i_alloc_sem is taken in shared mode and released | ||
1149 | * on I/O completion (which may happen asynchronously after returning to | ||
1150 | * the caller). | ||
1151 | * | ||
1152 | * - if the flags value does NOT contain DIO_LOCKING we don't use any | ||
1153 | * internal locking but rather rely on the filesystem to synchronize | ||
1154 | * direct I/O reads/writes versus each other and truncate. | ||
1155 | * For reads and writes both i_mutex and i_alloc_sem are not held on | ||
1156 | * entry and are never taken. | ||
1157 | */ | ||
1139 | ssize_t | 1158 | ssize_t |
1140 | __blockdev_direct_IO_newtrunc(int rw, struct kiocb *iocb, struct inode *inode, | 1159 | __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, |
1141 | struct block_device *bdev, const struct iovec *iov, loff_t offset, | 1160 | struct block_device *bdev, const struct iovec *iov, loff_t offset, |
1142 | unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, | 1161 | unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, |
1143 | dio_submit_t submit_io, int flags) | 1162 | dio_submit_t submit_io, int flags) |
@@ -1233,57 +1252,4 @@ __blockdev_direct_IO_newtrunc(int rw, struct kiocb *iocb, struct inode *inode, | |||
1233 | out: | 1252 | out: |
1234 | return retval; | 1253 | return retval; |
1235 | } | 1254 | } |
1236 | EXPORT_SYMBOL(__blockdev_direct_IO_newtrunc); | ||
1237 | |||
1238 | /* | ||
1239 | * This is a library function for use by filesystem drivers. | ||
1240 | * | ||
1241 | * The locking rules are governed by the flags parameter: | ||
1242 | * - if the flags value contains DIO_LOCKING we use a fancy locking | ||
1243 | * scheme for dumb filesystems. | ||
1244 | * For writes this function is called under i_mutex and returns with | ||
1245 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | ||
1246 | * taken and dropped again before returning. | ||
1247 | * For reads and writes i_alloc_sem is taken in shared mode and released | ||
1248 | * on I/O completion (which may happen asynchronously after returning to | ||
1249 | * the caller). | ||
1250 | * | ||
1251 | * - if the flags value does NOT contain DIO_LOCKING we don't use any | ||
1252 | * internal locking but rather rely on the filesystem to synchronize | ||
1253 | * direct I/O reads/writes versus each other and truncate. | ||
1254 | * For reads and writes both i_mutex and i_alloc_sem are not held on | ||
1255 | * entry and are never taken. | ||
1256 | */ | ||
1257 | ssize_t | ||
1258 | __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, | ||
1259 | struct block_device *bdev, const struct iovec *iov, loff_t offset, | ||
1260 | unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, | ||
1261 | dio_submit_t submit_io, int flags) | ||
1262 | { | ||
1263 | ssize_t retval; | ||
1264 | |||
1265 | retval = __blockdev_direct_IO_newtrunc(rw, iocb, inode, bdev, iov, | ||
1266 | offset, nr_segs, get_block, end_io, submit_io, flags); | ||
1267 | /* | ||
1268 | * In case of error extending write may have instantiated a few | ||
1269 | * blocks outside i_size. Trim these off again for DIO_LOCKING. | ||
1270 | * NOTE: DIO_NO_LOCK/DIO_OWN_LOCK callers have to handle this in | ||
1271 | * their own manner. This is a further example of where the old | ||
1272 | * truncate sequence is inadequate. | ||
1273 | * | ||
1274 | * NOTE: filesystems with their own locking have to handle this | ||
1275 | * on their own. | ||
1276 | */ | ||
1277 | if (flags & DIO_LOCKING) { | ||
1278 | if (unlikely((rw & WRITE) && retval < 0)) { | ||
1279 | loff_t isize = i_size_read(inode); | ||
1280 | loff_t end = offset + iov_length(iov, nr_segs); | ||
1281 | |||
1282 | if (end > isize) | ||
1283 | vmtruncate(inode, isize); | ||
1284 | } | ||
1285 | } | ||
1286 | |||
1287 | return retval; | ||
1288 | } | ||
1289 | EXPORT_SYMBOL(__blockdev_direct_IO); | 1255 | EXPORT_SYMBOL(__blockdev_direct_IO); |