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scst: Improve scst_adjust_sg() documentation

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git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@8930 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2020-05-17 19:57:13 +00:00
parent 54ccb1add2
commit b30634f6e0
1 changed files with 48 additions and 13 deletions
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scst/src/scst_lib.c
+48 -13
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@@ -3294,6 +3294,18 @@ next:
return;
}
/**
* __scst_adjust_sg - reduce the length of a scatterlist
* @cmd: [in] SCST command that owns the scatterlist.
* @sg: [in/out] Scatterlist of which to reduce the length.
* @sg_cnt: [in/out] Number of elements of the scatterlist.
* @adjust_len: [in] New length of the scatterlist in bytes.
* @orig_sg: [out] Information needed to restore the original scatterlist.
*
* Return:
* True if @adjust_len was less than or equal to the length of @sg; false
* otherwise.
*/
static bool __scst_adjust_sg(struct scst_cmd *cmd, struct scatterlist *sg,
int *sg_cnt, int adjust_len, struct scst_orig_sg_data *orig_sg)
{
@@ -3334,9 +3346,11 @@ static bool __scst_adjust_sg(struct scst_cmd *cmd, struct scatterlist *sg,
return res;
}
/*
* Makes cmd's SG shorter on adjust_len bytes. Reg_sg is true for cmd->sg
* and false for cmd->write_sg.
/**
* scst_adjust_sg - reduce the length of the scatterlist of a command
* @cmd: [in/out] SCST command that owns the scatterlist.
* @reg_sg: [in] True selects cmd->sg; false selects cmd->write_sg.
* @adjust_len: [in] New length of the scatterlist in bytes.
*/
static void scst_adjust_sg(struct scst_cmd *cmd, bool reg_sg,
int adjust_len)
@@ -3380,6 +3394,21 @@ static void scst_adjust_sg(struct scst_cmd *cmd, bool reg_sg,
return;
}
/**
* __scst_adjust_sg_get_tail - reduce a scatterlist to its tail
* @cmd: [in] SCST command that owns the scatterlist.
* @sg: [in/out] Scatterlist of which to reduce the length.
* @sg_cnt: [in/out] Number of elements of the scatterlist.
* @res_sg: [out] Pointer to first scatterlist element of the tail.
* @res_sg_cnt: [out] Number of scatterlist elements in the tail.
* @adjust_len: [in] New length of the scatterlist in bytes.
* @orig_sg: [out] Information needed to restore the original scatterlist.
* @must_left: [in] How many bytes must remain in @res_sg to consider the
* operation successful.
*
* Return:
* 0 upon sucess; a negative value upon error.
*/
static int __scst_adjust_sg_get_tail(struct scst_cmd *cmd,
struct scatterlist *sg, int *sg_cnt,
struct scatterlist **res_sg, int *res_sg_cnt,
@@ -3461,18 +3490,24 @@ out:
return res;
}
/*
* Returns in res_sg the tail of cmd's adjusted on adjust_len, i.e. tail
* of it. In res_sg_cnt sg_cnt of res_sg returned. Cmd only used to store
* cmd->sg restore information.
/**
* scst_adjust_sg_get_tail - reduce a scatterlist of a command to its tail
* @cmd: [in] SCST command that owns the scatterlist. Information
* about how to restore the scatterlist will be stored
* in @cmd.
* @res_sg: [out] Pointer to first scatterlist element of the tail.
* @res_sg_cnt: [out] Number of scatterlist elements in the tail.
* @res_dif_sg: [out] Pointer to first scatterlist element of the DIF tail.
* @res_dif_sg_cnt: [out] Number of scatterlist elements in the DIF tail.
* @adjust_len: [in] New length of the scatterlist in bytes.
* @must_left: [in] How many bytes must remain in @res_sg to consider the
* operation successful.
*
* Parameter must_left defines how many bytes must left in res_sg to consider
* operation successful.
* Return:
* 0 upon success; a negative value upon error.
*
* Returns 0 on success or error code otherwise.
*
* NOTE! Before scst_restore_sg_buff() called cmd->sg is corrupted and
* can NOT be used!
* NOTE! Until scst_restore_sg_buff() is called, @cmd->sg is corrupted and
* must NOT be used!
*/
static int scst_adjust_sg_get_tail(struct scst_cmd *cmd,
struct scatterlist **res_sg, int *res_sg_cnt,